BIO 580 - Medical Microbiology - Introduction - The Dynamic Nature of Infectious Disease

BIO 580 Medical Microbiology Unit 1 The Adversaries 50

The Dynamic Nature of Infectious Disease

Lecture 1 Objectives:

Understand that infectious disease is dynamic; diseases emerge and disappear, and perhaps re-emerge over time. The major diseases of our past may not be the major diseases of today. New diseases will continue to emerge in the future. Understand the major factors that influence why a new disease emerges, especially factors that can be influenced by human activity.

Overview of human history with infectious disease:

Year

Event

Homework ID microbial agent of disease as virus (V), bacterium (B), protozoa (P), Fungi (F)

1876

Koch proves that a specific microbe (Bacillus anthracis) causes a specific disease (Anthrax)

1885

Pasteur treats a boy post-exposure, with attenuated rabies

1918-19

Pandemic of Influenza A H1N1 (Spanish Flu) kills 500,000 Americans, 50 million worldwide

1928

Penicillium discovered to kill Staphylococcus

1944

Penicillin introduced into general clinical practice

1952

Staphylococcal strains demonstrate resistance to penicillin

1962

Machupo emerges in Bolivia

1967

Marburg terrorizes Germany

1969

Emergence of Lassa in Nigeria

1975

Global vaccination campaign eradicates smallpox

1976

Emergence of Ebola in Zaire

Emergence of Lyme disease (Borrelia bergdorferi)

182 American Legionnaires get sick in Philadelphia, 29 die (Legionella pneumophilia)

Emergence of penicillin resistant Neisseria gonorrhoea

1977

Gonorrhea triple antibiotic resistant

June 1981

CDCs Morbidity and Mortality Weekly Report describes a curious new health problem in American homosexuals

1983

1,000th official AIDS case documented

1984

Causative agent of AIDS identified - HIV

1990

Jim Henson is killed by a new stain of Streptococcus

1991

Drug resistant tuberculosis surfaces in the US

1993

4 children die of E. coli hemorrhagic syndrome

Sin Nombre emerges in the Four Corners area

1996

Recognition of BSE and nvCJD

Vancomycin-resistant S. aureus reported in Japan

1997

Vancomycin-resistant S. aureus reaches Michigan

Bird flu(Influenza A H5N1) in Hong Kong

1999

West Nile seen in U.S. for first time

2002

West Nile reaches west coast

2003

SARS-CoV emerges

2009

Influenza A (H1N1) first Influenza pandemic in 40 yrs

Preparation for next class meeting:

Write the take home message from today in a single sentence in the space below:

Read in the text Introduction and Chapters 1, 2, and 3 (We will discuss the info in order Ch. 1, 3, 2).

Terminology Find definitions for these terms. You may use one of the on-line medical dictionaries on our course web site http://www.cst.cmich.edu/users/alm1ew/MM%20Index%20Page.html

Used in Lecture 1

Infectious disease - any change from a state of health in which part or all of the host body is not capable of carrying on its normal functions due to the presence of a parasite or its products.

Parasite -

Attenuated

Pandemic

Eradicate -

Unit One - The Adversaries

Unit One - Outline of Topics

1. Review of Microbes (viruses, bacteria, fungi, protozoa, helminths, arthropods, normal microbiota)

1. Host Defenses

1. Nonspecific Defenses

1. Defenses against entry

1. Physical

1. Chemical

b. Biological

1. Defenses of the interior

1. Complement cascade

1. Acute phase proteins

1. Interferons

1. Phagocytic cells

1. polymorphonuclear leukocytes

1. monomorphonuclear leukocytes

1. Nonspecific cytolytic cells

1. Specific Defenses

1.T lymphocytes

1. Recognition of specific antigen (TCR and MHC)

1. Activation against a specific antigen (role of APC and TH)

1. Response to specific antigen

1. T helpers

1. T cytotoxic

1. T regs

2.B lymphocytes

1. Recognition of specific antigen (BCR)

1. Activation against a specific antigen (role of APC and TH)

1. Response to a specific antigen

i.Plasma cells

3. Memory cells (primary vs secondary response)

Unit One - Background Terminology/Concepts will not be covered in lecture

Obligatory Steps For Infectious Microbes:

Phenomenon

Step

How

1. Entry

attach and enter into body

evade host's natural protective and cleansing mechanisms

2. Spread

local or general spread in body

evade natural barriers and immediate local defenses

3. Multiplication

multiply

but many offspring will die in host

4. Evasion

evade host defenses

evade phagocytic and immune defenses long enough for full cycle in host to be completed

5. Transmission

exit from body

leave body at a site and on a scale that ensures spread to fresh host

6. Pathology

cause damage in host

not strictly necessary but often occurs

Pathogen - agent capable of causing disease

Pathogenicity ability to cause disease

Frank pathogen= obligate pathogen causes disease in a healthy host by direct interaction

Opportunistic pathogen- may cause disease under the right conditions

Virulence degree or intensity of pathogenicity.

Dependent on:

1. Invasiveness ability of organism to spread

1. Infectivity ability of organism to leave point of entry

1. Pathogenic potential degree pathogen causes damage

Virulence factors individual characteristics of a specific strain of microbe that confer virulence

Colonization (esp. by bacteria/yeast) establishment of a site of replication dependent on attachment

Symbiosis - an association of two different species of organisms.

Commensalism - one species uses the body of another species as a habitat and possibly as a source of nutrition.

Mutualism - a reciprocal relationship between two species.

Parasitism - one species in a relationship benefits and the other does not.

------

Respiration - use electron transport chain with an external e- acceptor (like O2 or NO3) as the terminal e- acceptor

Fermentation - no external e- acceptor, one of the substrates involved accepts the e-

Facultative fermenter will respire in the presence of external electron acceptors and ferment in their absence (Ex. Escherichia coli)

Obligate aerobe - must have O2 because only O2 can serve as the terminal e- acceptor (Ex. Bacillus spp.)

Facultative anaerobe - will use O2 for aerobic respiration if its present but will switch to fermentation or anaerobic respiration if no O2 (Ex. E. coli)

Aerotolerant anaerobe - can't use O2 as an external e- acceptor, but not killed by it.

Strict or obligate anaerobe - killed by exposure to O2 (Ex. Bacteroides fragilis)

BIO 580 Medical Microbiology Unit 1 The Adversaries 4

Microaerophilic - grows optimally in presence of oxygen concentrations that are below atmospheric concentrations (ex. the streptococci)

UNIT ONE THE ADVERSARIES

I. The Microbes

Objectives:

To Review:

1. important structural features of viruses

1. sequence of steps during viral infection

1. consequences of viral infections at a cellular level

1. important structural features of bacteria

1. key differences between Gram positive and Gram negative cell walls

1. clinical significance of LPS, capsules, flagella, fimbriae, and pili

1. important features of eukaryotic pathogens: fungi, protozoa, helminths, arthropods

1. distribution and significance of normal microbiota by way of clinical cases

A. VIRUSES - Obligate intracellular parasites

Common structural features

1. Genetic material - DNA or RNA, ss or ds

2. Outer coat - capsid - composed of subunits called capsomers

Nucleic acid + capsid = nucleocapsid

Only nucleocapsid = naked

Nucleocapsid surrounded by a lipid and protein envelope = enveloped

*Outer surfaces (capsids or envelopes) impt cause they 1st make contact w/ host cells.

Viral infection of host proceeds through several steps:

1. Entry into body of host - 4 routes

1) inhalation of droplets -

2) ingestion -

3) direct transfer -

4) bites of arthropod vectors -

2. Adsorption to target cell(s) in host specific interaction between virus surface molecules and receptors on target cells ***

3. Entry into target cell - 3 mechanisms

1) Fusion (enveloped)

2) Receptor-mediated endocytosis (RME)

(naked & enveloped)

Entry step ends with release of viral nucleic acid inside host target cell.

4. Multiplication w/in the target cell (obligate intracellular) complex process

1) synthesis of viral mRNA

DNA viruses may use host RNA polymerase -- viral DNA viral mRNA

RNA viruses have to use viral RNA polymerases

1. translation of viral proteins in host cytoplasm using host ribosomes viral mRNA can displace host mRNA

1. replication of viral nucleic acid

1. assembly of nucleic acid & capsomers into new nucleocapsids (= viral progeny)

5. Release from host cell (immediate or delayed) 2 mechanisms

1) lysis -

2) budding (acquisition of envelope)

Pathology - effects of viral infection on the targeted cell

1. lysis

1. persistence

1. latency ( lytic)

1. transformation

CONCEPT CHECK - Viruses

In the space below, in your own words, describe in complete detail:

1) the significance of surface projection target cell receptor interactions in viral infections

2) the two mechanisms by which an enveloped virus may enter into a target host cell

B. BACTERIA - prokaryotes

Common structural features

1. Genetic material ds, circular DNA = chromosome

2. Ribosomes are only organelle 70S (30S + 50S)

3. Cell membrane site of many metabolic functions (e.g., respiration)

4. Cell wall shape, rigidity, strength; impt in virulence and immunity

Compound responsible for strength of cell wall is peptidoglycan (hexose sugars + amino acids) unique to bacteria

Differences in cell wall structure - Gram positive vs. Gram negative

Gram positive

peptidoglycan layer is thick

1. highly polar hydrophilic surface

1. Lipoteichoic acids = LTA

1. resists activity of bile

1. digested by lysozyme

1. synthesis is disrupted by penicillin and cephalosporin antibiotics (more in Unit 4)

Gram negative

peptidoglycan layer is thin, overlaid by outer membrane that contains lipopolysaccharide and lipoprotein

1. outer membrane is polar, but lipids are hydrophilic

1. Lipopolysaccharide = LPS

0. carbohydrates antigenicity

0. lipid A is toxic = endotoxin induces fever, increases vascular permeability, may result in shock. etc. (more Units 2 & 3)

5. Structures exterior to the cell wall in some bacteria (more common in pathogens)

a. Capsule high molecular weight polysaccharides slimy and sticky

clinically relevant for 2 reasons

1) attach to a wide variety of surfaces *

2) more resistant to engulfment by host defense cells **

b. Flagella

1) allow bacteria to move

2) proteins are strongly antigenic/immune stimulating

c. Fimbriae (aka common pili, esp. in the Neisseria)

1) attachment (fimbriae adhesins to target cell membranes)

2) evading engulfment

d. Pili (aka sex pili)

1) exchange of genetic info, incl. antibiotic resistance (more in Unit 4)

Bacterial infection of host proceeds through several steps:

0. Entry into body of host 3 routes

1) direct contact

2) ingestion

3) fomites (inanimate objects)

0. Adhere to, colonize, (and possibly invade) host tissues or cells (infection may be extracellular or intracellular)

0. Evasion of host defenses (more in Unit 2)

0. Multiplication in the host (extracellular or intracellular)

0. Pathology (more in Units 2 and 3)

1) toxins

2) host immune response

0. Transmission to new hosts usually passive in body fluids

EUKARYOTIC PATHOGENS

C. FUNGI

1. Morphology

1. cell wall contains chitin; plasma membrane contains ergosterol

1. yeastvsmold

hyphae mycelium

Dimorphic - 2 forms yeast and mold

2. Reproduction moldvsyeast

sporesdivision

budding

3 types of fungal infections = mycoses

1) superficial

2) subcutaneous

3) systemic or deep -

Infections are most serious in immunocompromised.

D. PROTOZOA

0. Infection

may be extracellular or intracellular

2. Evasion of host defenses

3. Reproduction

asexual in humans, sexual absent or in insect vector.

4. Transmission

bites of insects

ingestion

sexually transmitted

E. HELMINTHS multicellular worms

1. Exs. tapeworms, flukes, nematodes

2. Have complex life cycles

3. Transmission

fecal-oral

ingestion of larvae in tissues

active penetration by larvae

bites of insects

F. ARTHROPODS

1. Exs. mosquitoes, biting flies, fleas, ticks, lice

1. increases potential for infection with viruses and protozoa

NORMAL MICROBIOTA = Indigenous microbiota (= Normal flora)

1. 1012 eukaryotic cells in adult human - 1013 prokaryotic

Clinical significance

1. common contaminants of clinical specimens

Fig 8.1 and Fig 8.2

2. opportunistic pathogens

In class mini clinical cases

Objectives:

1. understand the multiple lines of defenses against microbial infection

1. recognize the signs of acute inflammation when presented in a clinical context and describe how each sign of acute inflammation is generated at a cellular/tissue level

1. know why/how the alternate complement cascade is activated, what the important molecules formed are, what their function is, and what the consequences of complement activation are

1. understand how complement and phagocytosis are integrated processes

1. compare and contrast PMNs and macrophages

1. understand the importance of direct cell-cell contact in phagocytosis and the relationships between capsules, opsonins, and phagocytosis

Terminology:

Inflammation - the bodys response to injury or infection, which may be acute or chronic.

Acute inflammation - the immediate defensive reactions to any injury. It involves swelling, redness, heat, and pain.

Edema - excessive accumulation of fluid in the tissues.

Erythema - abnormal flushing of the skin caused by dilation of the blood capillaries.

BIO 580 Medical Microbiology Unit 1 The Adversaries 17

Opsonin - a molecule that attaches to cells, provides a bridge to receptors on phagocytic cells, and enhances the rate of phagocytosi

Cells of the Immune System

(White Blood Cells = WBC = leukocytes)

MonocytesMononuclear

Macrophages (differentiated monocytes, found in tissues)leukocytes

(agranulocytes)

Phagocytes

Neutrophils

EosinophilsPolymorphonuclear

Basophilsleukocytes

Mast cells (differentiated basophils, found in tissues)(granulocytes)

Natural Killer (NK) cellsLarge Granular Lymphocytes (LGL)

Killer (K) cells

Cytotoxic T cell (TC)

LymphocytesHelper T cell (TH)T lymphocytes (T cells)

Regulatory T cell (Tregs)

Effector B cells/ Plasma cellsB lymphocytes (B cells)

Origins of Cells of the Immune System

II. HOST DEFENSES

The immune system is composed of 2 arms

1. innate = nonspecific already in place, response is rapid, not as efficient

1. adaptive = specific must be induced, response is slower, highly efficient, enhances nonspecific. Has memory

A. Nonspecific Defenses

1. Defenses against entry into the host (1st line defenses)

1. Physical defenses (examples)

1. epithelial cells

2. turbulence

3. shedding, scraping, flushing (saliva, urine)

4. muco-ciliary clearance (1-3 cm/hr)

1. Chemical defenses (exs)

1. acids (e.g. gastric, fatty acids)

2. enzymes (e.g. lysozyme in saliva, tears, perspiration, urine)

3. other microbicidal chemicals (e.g. zinc, dermicidin)

1. Biological defenses (exs)

1. normal microbiota physical, competition, inhibitory substances

2. immune defense cells and molecules

2. Defenses of the interior of the host (2nd line defenses)

Inflammation

a. phagocytic cells

b. cytolytic cells

c. acute phase proteins

i. CRP

ii. interferon

iii. complement

Inflammation - a process that coordinates and regulates all aspects of non-specific interior defense.

Acute inflammation is characterized by:

1. increased blood supply to the area

2. increased capillary permeability

3. accumulation of neutrophils

Signs of acute inflammation 4 signs

1.

2.

3.

4.

Triggers of acute inflammation 2 triggers

1. cell/tissue damage/injury chemical alarms

2. cell wall components of bacteria (peptidoglycan, LTA, LPS)

How Signs of Acute Inflammation are Produced

1. release of Inflammatory Mediators (=IM; see table 9.3)

2. vaso-dilation & blood flow

2. endothelial cells of vessels contract

3. plasma leaks out of vessels & into tissues = exudation

4. swelling pressure on nerve endings

bradykinin

***Increased blood flow & capillary permeability - a mechanism for white blood cells and critical soluble factors to enter the tissues to combat microbial invaders.

The Critical White Blood Cells (WBC = leukocytes)

a. Phagocytes professional engulfing cells

2 main roles for phagocytes

1. engulf and destroy foreign matter

2. secrete chemicals (esp. cytokines)

Cytokines: (see table 11.2)

0. small secreted proteins that mediate and regulate inflammation, immunity, and hematopoiesis

0. act over short distances, short duration, and low conc.

0. receptor binding induces signal transduction and transcription and translation

2 main kinds of professional phagocytic cells

1. polymorphonuclear leukocytes (= PMN = polymorph = neutrophils) are granulocytes -

2. mononuclear leukocytes - monocytes & macrophages are agranulocytes -

1. polymorphonuclear leukocyte

dominant cell type in early stages acute inflammatory response

made in the bone marrow - 80 mil/min

dominant WBC, ~5,000/ul of blood - 15,000-20,000/ul

live for 2-3 days - function in anaerobic environments

abundant cytoplasmic granules contain loads of antimicrobial enzymes and chemicals, esp. lysozyme

best with extracellular pathogens, esp. bacteria

2. mononuclear leukocyte

majors players later in inflammatory process

made in bone marrow

in the blood - monocytes (~600/ul); in tissues - macrophages (~60,000)

conc. in lung, liver, lymph nodes, spleen

live for months-years

fewer granules (acid hydrolases, peroxidase)

one of the antigen presenting cells

secrete lots of different proteins (incl. lysozyme, nitric oxide, cytokines, complement factors)

BIO 580 Medical Microbiology Unit 1 The Adversaries 30

best with intracellular pathogens

Process of Phagocytosis 6 steps

1. Activation phagocytes are circulating with the bloodstream, need to move to the site of inflammation.

1. margination

1. pavementing

1. diapedesis

1. Migration via chemotaxis phagocytes have receptors for chemoattractant molecules, will track a concentration gradient of these molecules to the site where they are being produced.

3-6. illustrated in diagram

1. Attachment phagocytosis cannot happen until the phagocyte makes direct contact with the surface of the microbe. That direct contact is mediated by receptors on the surface of the phagocyte.

Pathogen-Associated Molecular Patterns

Microbe - PAMP PRR phagocyte

Pattern Recognition Receptors

PAMP incl. LTA & LPS (table 9.2)

After PAMP-PRR interaction, macrophages secrete pro-inflammatory cytokines (TNF, IL-1)

enhance antigen-presentation leads to activation of Th1. Well talk about this later.

1. Engulfment

1. Phagosome-lysosome fusion and intracellular killing

1. Expulsion of debris

Phagocytosis - Diagram

Role of Opsonins in Process of Phagocytosis - Diagram

(review definition of opsonin)

Opsonin

Interaction

Rate of Phagocytosis

Microbe

+phagocyte

none

present

Phagocyte Intracellular Killing Mechanisms

1. Oxygen-dependent killing (see box 9.2, p. 83) PMN and macrophages

oxidative burst

Reductionsuperoxide anionO2-

O2hydrogen peroxideH2O2 Reactive Oxygen

NADPHNADPsinglet oxygen1O2 Intermediates (ROI)

hydroxyl radicalsOH

(phagosome membrane)Other reactive intermediates

1. reactive nitrogen (nitric oxide = NO) (macrophages)

1. reactive chlorine (OCl) + myeloperoxidase (PMN)

2. Oxygen-independent killing compounds contained in cytoplasmic granules (see Table 14.2, p. 153)

1. acid hydrolases (PMN)

1. cathepsin G (PMN)

1. cationic proteins (PMN, eosinophils)

1. defensins (PMN)

1. lactoferrin (PMN) -

1. lysozyme (PMN, macrophage)

1. peroxidase (eosinophils)

b. Cytolytic Cells

1. natural killer cells (NK)(LGL)

target - intracellular pathogens, primarily viruses

attach by way of receptors to glycoproteins on infected cells

release - perforins (membrane channels) granzyme (apoptosis)

also secrete TNF

also secrete -IFN, impt early source, can activate macrophages

2. basophils and mast cells

target parasites

can be triggered to discharge cytoplasmic granules

release histamine, heparin, anaphylactic factors

3. eosinophils

target - large parasites (e.g. helminthes)

can be triggered to discharge cytoplasmic granules

release basic proteins, perforins, ROI chemical burns

c. The Critical Soluble Factors

Acute Phase Proteins

Plasma proteins proteins that increase in concentration 2-100X during the acute phase of an infection, in response to cytokines (IL-1, TNF).

i.. C-reactive protein (CRP) produced by liver - uses pattern recognition to bind to bacteria

1. acts as an opsonin

1. activates complement cascade

1. often used to monitor inflammation

ii. Interferons

Interferons first recognized because they interfere w/ viral replication

3 classes of Interferons:

1. - produced by leukocytes (WBC) anti-viral - prod w/in 24h

2. - produced by fibroblasts and other cells anti-viral - prod w/in 24 h

3. - produced by NK and esp. T lymphocytes anti-viral and involved in cell-cell communication.

iii. Complement - activation of the alternate cascade (= properdin pathway) - A group of 20 serum proteins form an enzymatic cascade

C3 (most abundant, prod. by liver cells)

C3aC3b

Factor B

C3bB

Factor D

C3bBb = C3 convertase

---------------------------------------------------------------------------------------------------------------------

C3C3

C3aC3b C3aC3b

C5 (prod by macrophages)

C5aC5b

C5b678 multiple C9

cell lysis

Opsonin

Interaction

Rate of Phagocytosis

Microbe

+phagocyte

none

C3b

CRP

Integration of Nonspecific Defenses

1. Stimulus

1. cell/tissue injury

inflammatory mediators released

1. microbial surface polysaccharides

1. Within seconds to minutes

1. acute inflammation begins

1. vaso-dilation of capillaries increases blood flow to/volume at the site

1. increased vascular permeability exudation of plasma, cells, and proteins

1. acute phase proteins increase in concentration

1. alternate complement cascade is activated

1. C3a and C5a mast cell degranulation

maintains vaso-dilation/vascular permeability

1. C5a attracts phagocytes from vasculature

1. C3b and C5b bind to cell surfaces

1. C3b opsonin

1. Minutes to hours

1. PMNs arrive in huge number and encounter cells opsonized by C3b and CRP phagocytosis is enhanced.

1. Hours to days

1. Interferons are produced

1. NK arrive

1. Macrophages arrive

SUMMARIZE Nonspecific Defenses

List the Nonspecific Interior Defenses important against Bacteria

List the Nonspecific Interior Defenses important against Viruses

CONCEPT CHECK Nonspecific defenses

Bubble Map

Characteristics unique to PMNShared characteristicsCharacteristics unique to macrophages

(MacrophagePMN)

CONCEPT CHECK Nonspecific defenses

Draw a concept map that illustrates the integration of complement and phagocytosis

CONCEPT CHECK - Nonspecific Host Defenses

Steve, a college student, was backpacking in a remote wilderness region with some friends. While pitching a tent, he tripped and fell. In an attempt to break his fall, he extended his arms and sustained a puncture wound to his right palm. Although the wound was painful and bled for a short time, it didnt appear to be serious, and Steve fell asleep that night unconcerned.

By the next morning, however, Steve noticed that the tissues immediately surrounding his wound were red, swollen, and warm. A round area about 1 inch in diameter really looked abnormal compared to the rest of his hand. The affected area was also painful, especially when he touched it or bumped it. After hiking all day, the sore hand was even more painful, and a thick yellow discharge oozed from the open wound. Steve felt unusually tired, his body ached, and a brief chill made him aware that he was getting a fever. His friends helped him elevate his arm and applied warm compresses to his palm, hoping that he would feel better in the morning.

1. List the nonspecific defenses against entry that are relevant to skin.

2. How were Steves skins defenses against entry overcome?

3. List the nonspecific interior defenses that would become activated in this case of bacterial invasion.

4. What are the signs in the case history that Steve is experiencing an inflammatory process? List them.

5. Describe the mechanisms at the cellular/tissue level that cause each of the signs of inflammation listed in 4 above?

Supplemental information FYI

Blood (modified from Wikipedia)

Blood accounts for 8% of the human body weight. The average adult has a blood volume of roughly 5 liters (1.3 gal), composed of plasma and several kinds of cells; these formed elements of the blood are erythrocytes (red blood cells; RBC), leukoytes (white blood cells; WBC), and thrombocytes (platelets). By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, and white cells about 0.7%.

Cells:

One microliter of blood contains:

1. 4.7 to 6.1 million (male), 4.2 to 5.4 million (female) erythrocytes. The proportion of blood occupied by red blood cells is referred to as the hematocrit, and is normally about 45%.

1. 4,00011,000 leukocytes. White blood cells are part of the immune system; they destroy and remove old or aberrant cells and cellular debris, as well as attack infectious agents and foreign substances.

1. 200,000500,000 thrombocytes: Platelets are responsible for blood clotting (coagulation). They change fibrinogen into fibrin. This fibrin creates a mesh onto which red blood cells collect and clot, which then stops more blood from leaving the body and also helps to prevent bacteria from entering the body.

Plasma:

About 55% of whole blood is blood plasma, a fluid that is the blood's liquid medium, which by itself is straw-yellow in color. The blood plasma volume totals of 2.73.0 liters (2.83.2 quarts) in an average human. It is an aqueous solution containing 92% water, 8% blood plasma proteins, and trace amounts of other materials. Plasma circulates dissolved nutrients, such as glucose, amino acids, and fatty acids (dissolved in the blood or bound to plasma proteins), and removes waste products, such as carbon dioxide, urea, and lactic acid.

Other important components include:

1. Serum albumin

1. Blood-clotting factors (to facilitate coagulation)

1. Immunoglobulins (antibodies)

1. lipoprotein particles

1. Various other proteins

1. Various electrolytes (mainly sodium and chloride)

The term serum refers to plasma from which the clotting proteins have been removed. Most of the proteins remaining are albumin and immunoglobulins.

Constitution of normal blood

Parameter

Value

hematocrit

45 7 (3852%) for males

42 5 (3747%) for females

pH

7.357.45

base excess

3 to +3

PO2

1013 kPa (80100 mm Hg)

PCO2

4.85.8 kPa (3545 mm Hg)

HCO3

2127 mM

oxygen saturation

Oxygenated: 9899%

Deoxygenated: 75%

Saliva (modified from Wikipedia) - Produced in salivary glands, human saliva is 98% water, but it contains many important substances, including electrolytes, mucus, antibacterial compounds and various enzymes

It is a fluid containing:

1. Water

1. Electrolytes: (sodium, potassium, calcium, magnesium, chloride, bicarbonate, phosphate, iodine)

1. Mucus. Mucus in saliva mainly consists of mucopolysaccharides and glycoproteins;

1. Antibacterial compounds (thiocyanate, hydrogen peroxide, and secretory IgA)

1. Epidermal growth factor or EGF

1. Various enzymes. There are three major enzymes found in saliva.

5. -amylase - starts the digestion of starch and lipase fat.

5.

5. s that kill bacteria: **

2.

2. Salivary

2.

5. -rich proteins (function in formation, Ca2+-binding, microbe killing and lubrication)

5. Minor enzymes

1. Cells: Possibly as much as 8 million human and 500 million bacterial cells per mL. The presence of bacterial products (small organic acids, amines, and thiols) causes saliva to sometimes exhibit foul odor.

1. , a newly researched pain-killing substance found in human saliva.

Lysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase, are a family of that damage bacterial cell walls by catalyzing of 1,4-beta-linkages between and residues in a and between residues in . Lysozyme is abundant in a number of secretions, such as , , , and . It is also present in granules of the (PMN).

Urine is approximately 95% water. The other components of normal urine are the solutes that are dissolved in the water component of the urine. These solutes can be divided into two categories according to their chemical structure (e.g. size and electrical charge).

Organic molecules These include:

1. Urea Makes up 2% of urine. Urea is an organic compound derived from ammonia and produced by the deamination of amino acids. The amount of urea in urine is related to quantity of dietary protein.

1. Creatinine - Creatinine is a normal constituent of blood. It is produced mainly as a result of the breakdown of creatine phosphate in muscle tissue. It is usually produced by the body at a fairly constant rate (which depends on the muscle mass of the body).

1. Uric acid - Due to its insolubility, uric acid has a tendency to crystallize, and is a common part of kidney stones.

1. Other substances/molecules - Example of other substances that may be found in small amounts in normal urine include carbohydrates, enzymes, fatty acids, hormones, pigments, and mucins (a group of large, heavily glycosylated proteins found in the body).

Ions These include:

1. Sodium

1. Potassium

1. Chloride

1. Magnesium

Calcium

1. Ammonium

1. Sulfates

Phosphates

Objectives:

1. understand how the appropriate lymphocytes are selected and activated and amplified

2. understand how immune cells talk with each other via cytokines

3. compare and contrast activation and response of T and B lymphocytes

4. compare and contrast the activation and response of Th1, Th2, and TC

5. understand the interactions between nonspecific and specific host defenses

6. understand how the specific immune response focuses the nonspecific response

7. understand the power of the secondary (anamnestic) immune response

B. Specific Defenses

1. = adaptive = acquired

1. 3rd line of defense only one with antigenic memory

1. based on lymphocytes

1. feedback into the nonspecific defenses enhance the effectiveness of the non-specific defenses

Specific immune system has to:

1. recognize

1. activate

1. respond

1. Overview

a. Recognition of antigen

A specific interaction between an antigen and a receptor

Anti gen

Antigens incl:

***proteins (incl. proteins + carbos or lipids) (T and B)

***complex polysaccharides (B only)

***nucleic acids (B only)

Full activation of the specific defenses involves several different types of immune cells working in concert:

1. non-specific cells (antigen-presenting cells)

1. specific cells (lymphocytes)

Antigen-Presenting Cell (APC)

Specialized cells that present microbial peptides (antigenic determinants) in a way that can be recognized by lymphocyte receptors.

Most significant: dendritic cells (tissues) > macrophages > B cells

Antigenic determinant (= epitope) a certain stretch of peptides from a larger microbial antigen

1. linear or conformational

1. small in size

2 main types of Lymphocytes

1. T lymphocytes (T cells)

1. B lymphocytes (B cells

Lymphocyte receptors (R)

1. constant region transmembrane

1. variable region interacts with microbial peptide

General Overview of Antigen Presentation - Diagram

Presentation of antigenic determinant by an APC to a lymphocyte occurs in draining lymph nodes (surfaces, tissues) or spleen (blood)

Initiates a chain of events that transforms a small, resting, nave lymphocyte into a highly active, functional lymphocyte (more later)

b. Activation from all the antigen nave lymphocytes,

selection of lymphocytes with complementary receptor that matches

specific microbial antigenic determinant

1. receive and secrete cytokines

2. undergo proliferation = clonal expansion

1104 105 - occurs in lymphoid organs

Results in an expanded population of immature effector

lymphocytes

3. differentiate into functional sub-types

effectors fight this time

memory reserves, to be deployed in the future

c. Response of activated effector sub-types

activated (= primed) effector T lymphocytes either:

1. kill infected cells

2. coordinate and regulate immune response

activated effector B lymphocytes (called plasma cells)

secrete antibodies

2. Add in specifics

T Lymphocytes

2 categories of T cells by surface marker called Cluster Determinant

1. CD4 - 2 functional types

1) T helper cells = TH - regulate the immune system by increasing the response ( by activating other immune cells).

a) Subset Th1

b) Subset Th2

2) T regulatory cells (=Tregs) - regulate the immune system by the response

2. CD8 =T cytotoxic cells =TC = CTL- kill cells infected w/ intracellular pathogens

a. Antigen Recognition by Antigen-Nave, Resting T lymphocytes

*T cell receptor interacts with microbial (foreign) antigenic determinant complexed with a self antigen

Self antigens Major Histocompatibility Complex (MHC) proteins protein molecules on the surface of cells that mark them as cells.

2 classes of MHC

Class I - on the surface of all nucleated host cells

Class II on the surface of APC

THR - recog. antigenic determinant complexed w/ Class II MHC + co-stimulatory interactions (depend on who the APC is)

TCR - recog. antigenic determinant complexed w/ Class I MHC + co-stimulatory interactions

b. Activation of T lymphocytes 3 steps

1. Receive cytokines from APC

ex. IL-1 from macrophage

1. # of IL-2R and secrete/receive IL-2 proliferation

Results in an expanded set of immature effector lymphocytes,

all with same receptor for antigenic determinant complexed

to MHC II (will all recognize the same microbial threat)

1. Differentiation into effector and memory T cells

(Tc, and NK)

c. Response of Effector T Lymphocytes

Each category of effector T cell has a unique response:

regulating the immune response = immunoregulation

enhance response - TH

subset Th1 secretes IL-2 stimulates Tc proliferation & maturation. Secretes -IFN activates effector TC , activates macrophages and NK to kill their intracellular pathogens; (down regulates Th2)

subset Th2 secretes IL-4 stimulates B cell proliferation & differentiation into plasma cells; (down regulates Th1)

suppress response - Tregs

OR

direct cell killing = cytotoxicity TC

secrete perforin transmembrane channels

secrete granzyme apoptosis

also secrete TNF

also secrete -IFN (activates NK and macrophages)

Integration via Lymphocyte Recognition, Activation, and Response - Diagram

B Lymphocytes

a. Antigen Recognition by B Lymphocytes

Receptor interacts with microbial (foreign) antigen alone receptor does not interact with MHC.

Can present antigen to Th2

b. Activation of B Lymphocytes

1. IL-2 from subset Th2 clonal expansion (= proliferation)

1. IL-4 from subset Th2 differentiation into effector (= plasma) and memory B cells

c. Response of Effector B lymphocytes (=Plasma Cells)

Secrete Antibody (Ab) at the rate of 1,000 molecules/min.

Antibody Structure - Diagram

Actions of Antibody Molecules focus the non-specific

1. bind to microbial antigen interfere with receptor interaction for any microbe that uses specific attachment sites = neutralizing

***2linking a bacterium to a phagocyte = opsonization (followed by phagocytosis)

Opsonin

Rate of Phagocytosis

Microbe

+phagocyte

none

-/+

C3b

+

CRP

+

Ab

C3b + Ab

3. linking many small antigens together = agglutination (followed by phagocytosis)

4. complement activation - classical pathway (followed by either opsonization and phagocytosis or lysis) (notes p.45)

5. ADCC - antibody dependent cellular cytotoxicity (notes p. 47)

Activation of Classical Complement Cascade - Diagram

C1

C2C4

C2bC2aC4bC4a

C2a4b

C3C3

C3aC3b C3aC3b

C5

C5aC5b

C5b678 multiple C9 (MAC)

Fill in:

Triggers

Important molecules

Consequences -

Timing

Complement activation enhances phagocytosis and inflammation and leads to cell lysis.

Classes of Antibody Molecules

Antibody = Immunoglobulin (Ig) proteins found in fluids in the body

5 Classes:

Class

Structure

%

Location

Roles

IgG

monomer

75-80

serum, extra vascular spaces, crosses placenta

fix complement

opsonin

IgA

monomer

dimer

15-21

serum, tears, saliva, mucus, colostrum

neutralizing

IgM

pentamer

6-7

serum, 1st made by virgin B cells, 1st made by fetus

fix complement

agglutinating

IgD

monomer