The Human Immune System:

Basics and then some…

Basic Components of the Immune System

• Pathogen, Bacteria, Viruses, Infections, and parasites

• Leukocytes

• Antibodies

• Antigens

Virus

Pathogens and all the other stuff

• Any biological agent that causes illness and/or disease to its host. Also known as a germs, simple as that!

Different types of pathogens include the following:

Leukocytes (White Blood Cells)

lymphocytesOther Types of

WBC

Eosinophils MacrophagesT cells NK CellsB Cells

White Blood Cells

Eosinophils and Macrophages

• Macrophage, “Big Eaters,” a form of White Blood Cell.

• Operates in both the Non-specific and Specific Immune Systems (to be explained later)

• Also a Phagocyte, which means it engulfs pathogens and cellular debris, and then proceeds to digest it, this process is known as Phagocytosis.

Macrophage!

Eosinophils are a type of White Blood Cell.

They fight infection and parasites.

They also play a role in Allergic reactions.

Eosinophils produce Interleukin 1 and Interleukin 2 (To be explained later as well).

Antibodies & Antigens

• Antigens= a fragment of a protein or peptide from the pathogen, taken to the surface of the infected cell and bound in an MHC (major histocompatibility complex) molecule.

• The class 1 MHC complex molecule and the foreign peptide form the antigen, which can be read by the receptors on Killer T cells.

CellClass 1 MHC molecule

Antigen

Pathogen

Antibodies are produced by B cells, when stimulated by lymphokines from helper T cells. The antibody attaches to the antigen, completing the signal, coding the infected cells for destruction.

Antibodies are constructed of DNA fragments, making them so unique and almost innumerable.

T cells!

T cells

Helper T cell (Th) Killer T cell (Tk)

Memory T cell Suppressor T cell

Helper T cell

Killer T cell

Suppressor T cells- in charge of slowing and stopping the immune response after the foreign substance is destroyed.

Helper T cells- secrete lymphokines that direct B cells into producing antibodies and also direct the Killer T cells as to which cell they get to eliminate.

Killer T cells- They find specifically coded infected cells, and then destroy them with cytotoxins. They may be directed by Helper T cells

Memory T cells- derived from Helper T cells, have the same properties as their parent cell, and circulates until the body encounters the pathogen its parent cells were designer for.

B cells

• B Plasma Cells- when the B cell produces the antibody for a specific antigen, it begins to clone itself into B plasma cells, that produce more of that particular binding antibody.

• These cells release immunoglobulin, or antibodies.

• B plasma cells have a 5 to 7 day life-span

• all its protein synthesis energy is going into the production of Antibodies, not self preservation.

• B Memory Cells- These are the same as B plasma cells, except they remain inactive until the secondary immune response

• Secondary immune response is considered anytime the body encounters a pathogen after the first time. Quicker response time.

• Primary response is the first time the body encounters a specific pathogen, Lag period before B cells respond.

NK Cells

• NK, stands for Natural Killers, meaning they do not need to be activated by a class 1 MHC receptor

• NK cells play a major role in the Innate Immune System

• Activated by interferons and macrophage-derived cytokines

• Contains a virus until killer T cells develop, and then kills the virus.

Now, the pieces come together…Immune System

Non-specific Response Specific Response

Complement System

Inflammatory Response

Interferon Response

Anti-body Mediated Response Cell Mediated Response

Fever Response

Non-Specific Immune Response

• Also Known as the “Innate Immune System

• Consists of:

Complement system, and three response types:

Fever Response,

Inflammatory Response,

Interferon Response

Inflammatory Response

• Occurs from Trauma.

• Releases Bradykinin

• Causing release of histamines.

• Histamine causes increased capillary dilation, subsequently increasing capillary permeability.

• Increase in fluids causes inflammation!

Bradykinin is a protein that stimulates pain sensors as well as causing the release of histamines

Interferon Response

• As the name suggests, they interfere…with viral replication!

• Once the virus infects the cell, the cell creates a chemical protein called Interferon!

• Interferon inhibits viral reproduction between cells by binding to the receptors of uninfected cells.

Fever Response

• The response to toxins in the body, produced by bacteria, is to increase the internal temperature of the body.

• This affect is enhanced when cells release Pyrogen, a cytokine that resets the bodies temp. Also known as Interleukin 1!

Complement System• Main component of the Innate Immune

System

• 3 primary ways to dispose of pathogens.

1.)Chemical stimulation causes the complement protein to bind with any cell, like bacteria. Binding triggers activation of other complements, as well as attracting phagocytes.

Complements can kill bacteria by punching a hole into their lipid membrane and essentially drowning them in water.

Foreign

Cell

2.) Some cells have sugar (polysaccharide) capsule shells, complement can’t directly bind.

So they’re either eaten by macrophages, or 3) bound to a macrophage that then releases IL-6,

IL-6 goes to the liver and produces a protein called Mannose. Mannose binds to the bacteria, allowing a complement to bind to it as well.

Interleukins

• A form of cytokine, they act like neurotransmitters for the immune system, relaying messages.

Of Note: Interleukin 1, 2, and 6

Interleukin 1: -Responsible for fever response-Controls some lymphocytes-Increases the number of bone marrow cells-Causes degeneration of joints between bones

Interleukin 2:

-Key in discriminating between Self and foreign cells

-Secreted by the binding of T cells to an antigen

- Stimulates growth, differentiation, and survival of killer T cells.

Interleukin 6:

-Secreted by macrophages, and sent to liver to produce Mannose, which is a protein that binds to sugars.

- Helps with inflammation, especially from burns

Specific Immune Response

• Also known as “Adaptive Immune System”

• Breaks down into two categories-

Antibody- Mediated Immune Response (AMIR)

Cell-Mediated Immune Response (CMIR)

Antibody Mediated Immune Response

• Also known as Humoral Immune Response

• The antibodies secreted by the B cells in AMIR attach to antigens and effectively “tag” specific cells for destruction, sparing the lives of the healthy cells.

Flow of AMIRMacrophages roam body, engulfing infected extracellular materials

Degrades engulfed material into peptides

Class 2 MHC presents the infected peptideAs an Antigen

Macrophage returns to lymph nodes w/ antigen

Antigen received by Helper T cells

Th Cells secrete lymphokines

Lymphokines direct B cells to release antibodiesAnd directs Tk cells to infected cells.

Tk kills infected cells tagged by antibodies

Flow of CMIR

Host cells carry class 1 MHC molecules to outside of cell

MHC binds to and displays peptide/protein fragment of pathogen

Parasite and MHC form antigenAntigen recognized by Killer T cell antigen receptors

Killer T cell releases cytotoxins into infected cells, and kills them

Immunological Memory

• The reason why vaccines make sense, and we eventually build a tolerance to certain diseases…

It’s because after every encounter with a pathogen, both the T cells and the B cells differentiate into an inactive form of their parent cell. They remain inactive until the second immune response for that specific pathogen.

Vaccination is an introduction of a dormant or dead pathogen, which allows are body to do its primary immune response without the risk of actual sickness.

Allergic reactions

• The allergy is the immune systems response to a harmless foreign substance, such as pollen or dust.

• Since the immune system is based primarily off of DNA, then it can be inferred that allergies are hereditary.

Self vs. Not Self

• Like most systems things can go wrong, such as when the immune system attacks itself, not recognizing the proteins that code a cell as “self.” When this happens it is known as an autoimmune disease.

• In the case of tissue implants, they may be rejected if the tissue cells don’t have the proper proteins to inactivate the complement system in a different humans body. So the complement kills the cells!

• In order for tissues to be accepted they also must have the proper MHC complex to pass as human cells, these proteins must be on the surface of the cells, as either of the two classes.

The Immune System presented differently

Immunological memory

CMIR

AMIR

Bibliography-Information• http://www.mmu.k12.vt.us/teachers/kefferm/humanbio/immune/how%20cells%20process%20Ag.pdf• http://www.mmu.k12.vt.us/teachers/kefferm/humanbio/immune/white%20blood%20cells%20writing.jpg• http://en.wikipedia.org/wiki/Immune_System• http://en.wikipedia.org/wiki/Pathogen• http://en.wikipedia.org/wiki/Cell-mediated_immunity• http://en.wikipedia.org/wiki/Humoral_immune_response• http://en.wikipedia.org/wiki/Cytokine• http://en.wikipedia.org/wiki/Interleukins• http://en.wikipedia.org/wiki/Interleukin_1• http://en.wikipedia.org/wiki/Interleukin_2• http://en.wikipedia.org/wiki/Lymphokine• http://en.wikipedia.org/wiki/Eosinophil_granulocyte• http://en.wikipedia.org/wiki/Natural_killer_cell• http://en.wikipedia.org/wiki/Lymphocyte• http://en.wikipedia.org/wiki/Macrophage#Phagocytosis• http://en.wikipedia.org/wiki/Allergy• The Human Biology Text book by Joseph Mannino• http://uhaweb.hartford.edu/bugl/immune.htm• http://en.wikipedia.org/wiki/Antibody• And many, many, many, many other wikipedia pages…

Bibliography-Pictures• https://services.epnet.com/GetImage.aspx/getImage.aspx?ImageIID=2508

• http://www.mmu.k12.vt.us/teachers/kefferm/humanbio/immune/how%20cells%20process%20Ag.pdf

• http://mmsmineraldrops.com/images/pathogens3.jpg

• http://en.wikipedia.org/wiki/Lymphocyte

• http://www.bio-pro.de/imperia/md/images/artikelgebunden/stern/nk_tumor_338x319.jpg

• http://uhaweb.hartford.edu/bugl/immune.htm

• http://tell.fll.purdue.edu/JapanProj/FLClipart/Verbs/fever.gif

• http://static.howstuffworks.com/gif/light-virus-1.jpg

• http://www.lipidnutrition.com/Images/MPE_059_gs%20copy%20adjusted%20pixels_tcm7-3751.jpg

• http://pathology.emory.edu/images/FacultyImages/CooperM.jpg

• http://www.gtdtimes.com/files/2008/05/memory.jpg

• http://upload.wikimedia.org/wikipedia/commons/4/4a/Hematopoiesis_simple.png

• http://www.modernforager.com/blog/wp-content/uploads/2008/03/96500b.jpg

Words of the Day!• Erythropoietin- glycoprotein that controls

red blood cell production.

• Haematopoiesis- the process of making blood cells from hematopoietic stem cells.

• Agammaglobulinemia- the inability to make antibodies

And then there’s this guy…