Immunology for Sx Dd

8/7/2019 Immunology for Sx Dd

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Immunology for SurgeryProf Anura Weerasinghe

MBBS(Col), MD(Col), DCH(Col),

DTM&H(London), MRCP(UK),FRCP(Edin) & PhD(Japan)

Professor of Physiology

Faculty of Medicine

University of Kelaniya

Ragama


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Topics

Immunity to cancer and transplantation

Immunodeficiency

Hypersensitivity Tolerance and autoimmunity


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Immune response againsttumours and transplants


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Objectives

Tumour and transplant antigens

Immune surveillance against tumour

cells Immunological mechanisms of rejection

and graft-versus-host disease (GVHD)


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Tumour antigens

Sparse evidence to support protective

immunity elicited by tumour antigens

May be used as tumour markers May be used as targets for tumour

vaccines

May be used as targets for antibodiesand effector T cells generated against

these antigens (Immunotherapy)


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Types of tumour antigens

Mutated self protein In melanoma

Product of oncogene

Her-2/neu in breast cancer Products of mutated tumour suppressor

gene

p53 in colon, breast & lung cancers


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Carcinogenesis

Defect in DNA

Chemical Physical

Biological


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DNA defect

Point mutationGene deletion

Chromosomal

translocation

DNA repair


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Types of tumour antigens

Mutated self protein In melanoma

Product of oncogene

Her-2/neu in breast cancer Products of mutated tumour suppressor

gene

p53 in colon, breast & lung cancers Aberrantly self protein

onco-foetal antigens


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Oncofetal antigens

Although highly associated with some

tumours, both on their cell surface and

in the serum, oncofetal antigens are not

unique to tumour cells since they are

also found on cells during embryonic

development and are found at very low

levels in normal human serum.


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Oncofetal antigens

Carcinoembryonic antigens (CEA)

- GI cancers

Alpha-fetoprotein

- Hepatoma


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Types of tumour antigens Mutated self protein

In melanoma

Product of oncogene

Her-2/neu in breast cancer

Products of mutated tumour suppressor gene p53 in colon, breast & lung cancers

Aberrantly self protein onco-foetal antigens

Oncogenic virus

HPV in cervical cancer EBV in lymphoma / Nasopharyngeal carcinoma

Hepatitis B in hepatoma


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That the immune system surveys constantly

for neoplastic cells and destroys them, is

suggested by the observation of increased

incidence of tumours of lymphoid or

epithelial cells in immunodeficient animals

and humans.


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Immune surveillance

The immune system surveys constantly

for neoplastic antigens associated with anewly developing tumour and destroys

the cells bearing them.


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Immune mechanisms operating

against tumours Activated macrophages

NK cells

Antibody and complement Antibody dependent cellular toxicity

Cytotoxic T cells


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Molecules involved in the

first-line defenseComplements - Promote action of

macrophages- lysis of the target cell

Cytokines - augment immune response

Eg; INF-K activate both macrophages

and NK cells


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Antibody mediated tumour

rejection

Play a role in leukaemia

Not very effective in solid tumours

Complementdependent

cytotoxicity

Antibody-dependentcellular cytotoxicity


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Complement mediated

cytotoxicity

Mediated by antibodies

Particularly IgM

Tumour cell + Antibody

Trigger classical complement pathway

C3b and C5b

Opsonization Lysis


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Antibody-dependent cellular

cytotoxicity

NK cells

+IgG

Sensitized tumour cell Release of cytotoxicmolecules

eg; perforin

Direct interaction

with tumour cells


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scuss t e ro e o o ow ng

cells/molecules in immune

response to tumours

T lymphocytes

NK cells

Macrophages

Antibodies


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Immunology of Transplantation

Immune Response to graft cells

Immunology of graft dysfunction

Strategies to prevent rejection

Treatment of acute rejection


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Immune response to graft

cells

Recognition

Self from non-self

Transplantation antigens

Histocompatibility Complexes

MajorMinor

Blood group antigens


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Immune Response to graft

cells

Presentation ofTransplantation antigens

APC T cell

T cell

T cell


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Immunology of Graft

Dysfunction

Hyperacute rejection (Within

minutes)

Unrecognized ABO incompatibility

Antibodies to HLA class I (positive

cross-match)

Acute (days or weeks)

CTL (CD8) mediated

Chronic (months or years)

CD4 mediated


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Humoral rejection

Antigen antibody Complexes

Activation of Complement cascade

Chemotaxis & Inflammation

Occlusion of capillaries & prevent vascularization


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Strategies to Prevent Rejection

Hyperacute/Acute- ABO compatibility

Tissue matchingImmunosuppresive

Therapy

Chronic - Careful tapering of

ImmunosuppressiveTissue matching


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GVHD

A disease occurring in BMT recipientsthat is caused by the reaction of mature

T cells in the marrow graft against

alloantigen in host cells. Requirements for GVHD;

Immuno-competent graft cells &

immuno-incompetent hostEg; blood transfusion in SCID


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Summary

Tumour and transplant antigens

Immune response in immune

surveillance against tumour cells Immunological mechanisms of rejection

and graft-versus-host disease


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Immunodeficiency


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Objectives

Classification of Immunodeficiency When to suspect

How to investigate


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Classification of

immunodeficiencies Primary usually congenital (inherited) The result of a failure of proper development

of the humoral or cellular immune system

Secondary acquired

The consequences of other diseases and

their treatments.


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Primary immunodeficiency

Complements Recurrent meningococcal meningitis

Phagocytes

Recurrent Staphylococcal skin sepsis Humoral immunity

Severe or recurrent extracellularbacterial

infections

Cellular immunity

Recurrent intracellularbacterial or viral

infections.


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Complement deficiency C3 deficiency

Recurrent infections with encapsulatedorganisms

Pneumococcus, Streptococcus & Neisseria

Deficiencies in Membrane Attack

Complex (MAC) components

Increased susceptibility to infections with

Meningococcus eg; Neisseria


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Extrinsic Phagocytic defects

resulting from

Deficiency of antibody or complement

Defective opsonization

Suppression of phagocytic activity

Eg by Glucocorticoids or autoantibodies


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B ll d fi i i


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B cell deficiencies Abnormal B cell maturation

Lack of Stem cells Severe Combined Immunodeficiency (SCID)

B cells fail to develop from B cell

precursors

Brutons agammaglobulinaemia

B cells do not switch antibody classes from

IgM

Hyper-IgM syndrome

B cells that do not respond to signals

from other cells

Common Variable Immunodeficiency

Transient h o amma lobulinaemia


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B cell deficiencies

Severe Combined Immunodeficiency

(SCID)

Functional impairment ofboth B and T

lymphocyte limbs of the immune response. Inheritance is either X-linked or autosomal

recessive

Brutons Agammaglobulinemia

X-linked inheritance

Isolated immunoglobulin defects

IgA deficiency is the commonest

C ll l I d fi i


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Cellular Immunodeficiency Result in recurrent viral, fungal,

mycobacterial and protozoan infections

Lack of Thymus

Di Georges syndrome

Stem cell defect

SCID


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DiGeorge syndrome;cellular immunodeficiency

Failure of the parathyroids

and thymus to develop

Appearance ofhypocalcemic tetany

shortly afterbirth

Occurs in both males and

famales A number of physical

abnormalities

P ti l C bi d I


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Partial Combined Immune

Deficiency

Wiskott-Aldrich Syndrome X-linked recessive disorder

Characterized by the presence of eczema,

thrombocytopenic purpura, and increasedsusceptibility to infection.

Ataxia-Telangiectasia

Autosomal recessive disorder

Ataxia

Telangiectasia

Recurrent sinopulmonary infections


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Molluscum contangiosum


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Secondary (acquired)

immunodeficiency

Commonest immunodeficiency

Contributes a significant proportion to

hospital admissions Mainly affects the phagocytic and

lymphocytic functions

Results from infection (HIV),malnutrition, aging, cytotoxic therapy

etc.

Factors causing secondary


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immunodeficiency

Malnutrition - Protein-calory malnutritionand lack of certain dietary elements (eg; Iron,Zinc); world-wide the major predisposingfactor for secondary immunodeficiency.

Tumors direct effect of tumors on theimmune system by effects onimmunoregulatory molecules or release ofimmunosppressive molecules, eg TGFF.

Cytotoxic drugs/irradiation widely usedfor tumor therapy, but also kills cells importantto immune responses, including stem cells,neutrophil progenitors and rapidly dividing

lymphoyctes in primary lymphoid organs.



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immunodeficiency

Aging decreased T and B cell responsesand changes in the quality of the response.

Trauma increased infections probably

related to release of immunosuppressivemolecules such as glucocorticoids.

Diabetes mellitus

Immunosuppressive microbes malaria,measles and HIV.


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When to suspect

Recurrent infections

Severe infections not responding to

appropriate antibiotics

Unusual infections

Opportunistic infections

Opportunistic cancers


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Investigations to assess

quantitative or qualitativedefects of

the antibody-mediated immunity

the cell-mediated immunity

the complement cascade

the phagocytes

Evaluation of antibody


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Evaluation of antibody

mediated immunity

Simple electrophoresis Quantitative estimation of immunoglobulins

IgA, IgG, IgM


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Evaluation of cell-mediated immunity

DTH skin tests to common antigens candida, tuberculin

Determine

Total lymphocyte count T cell number in blood

T cell subpopulation percentages

(eg; CD4 & CD8)

E l i f ll di d


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Evaluation of cell-mediated

immunity

Delayed type of

hypersensitivity

skin tests tocommon

antigens eg;

Tuberculin

Mantoux test


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Flowcytometer

Evaluation of the complement


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Evaluation of the complement

cascade

Quantitative estimation of individualcomplement components


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Evaluation of the phagocytic

functions

Determine total granulocyte and

monocyte count

Assay for

Phagocytosis

Nitroblue tetrazolium (NBT) assay

Chaemotaxis

Diagnosis and treatment of


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Diagnosis and treatment of

immunodeficiency

Family history Since defective genes canbe inherited, an investigation into the family

history is especially important in the diagnosis

of primary immunodificiencies

Evaluation of specific immune

components

Antibiotics and antibodies Antibiotic

therapy is the standard treatment forinfections. In addition, antibodies from a pool

of donors are used for antibody deficiencies

Bone marrow transplants and gene


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Summary

Classification

When to suspect

How to investigate


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Hypersensitivity

Obj i


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Objectives

List hypersensitivity reactions anddescribe

Immunopathological basis

Clinical presentations

Principles of management of each type

Describe the management of

anaphylactic shock


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Immune response

Protective Damage to

host tissues

Hypersensitivity

Autoimmunity

Original Classification of


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Original Classification of

hypersensitivity by Gell and

Coombs

Type Immune mechanisms

I IgE antibodies

II Ab & complement

III Ag/Ab complexes

IV T cell mediated

P t l ifi ti f


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Present classification of

hypersensitivity

Gell & Coombs classification

of hypersensitivity

+

Type V Antibody mediated(stimulatory or blocking)

Ti f


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Time of appearance

Type I 2 to 30 minutes(immediate)

Type II

(Cytotoxic)

5 to 8 hours

(Intermediate)

Type III

(Immune complex)

2 to 8 hours

(Intermediate)

Type IV 24 72 hours

(delayed)

IgE mediated Type 1


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IgE mediated Type 1

hypersensitivity: Allergy

Commonest type of hypersenisivity Range from mild to fatal (anaphylaxis)

Some individuals (atopic) have a

genetic predisposition to make highlevels of IgE

Allergy affects 17% of the population

Allergic reaction can occur to normally,harmless antigens (such as pollen or

foodstuffs) and microbial antigens (fungi

or worms)

Mechanism of type 1


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Mechanism of type 1

hypersensitivity

Degranulate:

Histamine

Products of

cell membrane

lipids:

Leukotrienes

Cytokines

PreformedB cell


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Mast cell

IgE

Allergen

Preformed

metabolites

- histamine

Products of

membrane lipids

- Leukotrines- ProstaglandinsIL-5

Eosinophil

IL-4B cell


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Clinical examples of type 1


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Clinical examples of type 1

hypersensitivity

Rhinitis

Anaphylaxis

Bronchial asthma

Urticaria/angio-oedema

Food allergy


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Urticaria Agio-oedema


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Diagnosis

History

Specific IgE antibody level

Skin prick test Food elimination & challenge

Note; Patch test is done in Type IV hypersensitivity

Skin Prick Test


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Skin PrickTest


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Treatment

Antigen avoidance

Antihistamine

Corticosteroids Leukotriene receptor antagonists

Mast cell stabilizers

Adrenaline

Type II hypersensitivity


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Type II hypersensitivity Cytotoxic hypersensitivity

IgG and IgM mediated

Antibodies are directed mainly

to cellular antigens (e.g. onerythrocytes) or surface

autoantigens

Causes damage through

opsonization, lysis or antibody

dependent cellular cytotoxicity

Clinical examples of type II


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hypersensitivity

Rhesus incompatibility IgG against RhD antigen

Transfusion reactions

Isohaemaglutinins against majorbloodgroup antigens (A & B)

Autoantigens

Basement membranes of lung & kidney -

Goodpastures syndrome Acetylcholine receptor Myasthenia gravis

Erythrocytes Haemolytic anaemia

Drugs


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SDL

Principles of Coombs test


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Treatment

Exchange transfusion

Plasmapheresis

Immunosuppressives/cytotoxics

Type III hypersensitivityI l di d


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Immune-complex mediated

IgG against non-self or self antigens

Eg; microbes, drugs including antisera &autoantigens (eg; SLE)

Activation of complement cascade

Local damage: Arthus reaction Inhalation ofbacterial spores Farmers

lung

Avian serum/faecal proteins Bird

fanciers lung Systemic damage:

Serum sickness

Vasculitis


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T


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Treatment

Corticosteroids

Immunosuppressives/cytotoxics

Plasmapheresis

Monoclonal antibodies

T IV h iti it


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Type IV hypersensitivity

Delayed type (Occurs 24 hours after

contact with antigens)

Mediated by cells (T cells together with

dendritic cells, macrophages and

cytokines)

Persistence presence of antigen leads to

the formation of granuloma


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Clinical examples for type IV


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Clinical examples for type IV

hypersensitivity Contact dermatitis with

Small molecular weight chemicals

Eg: Nickel, silica

Molecules from some plants Eg; poison ivy

Post primary tuberculosis

Tuberculin test (Mantoux test)

T t t


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Treatment

Immunosuppressives

Corticosteroids

Removal of antigen

T V h iti it


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Type V hypersensitivity

Blocking antibodies

Anti-AChR antibodies in myasthenia gravis

Blocks muscle contraction

Stimulating antibodies

Anti-TSHR antibodies in Graves disease

Excess thyroid hormone secretion

T t t


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Treatment

Treatment of individual disease


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S


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Summary

Classification of hypersensitivity

Immunopathogenesis

Clinical features

Principles of management

of each type


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Tolerance & Autoimmunity

Objectives


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Objectives Define tolerance

Mechanisms of tolerance

Define autoimmunity and

autoimmune disease

Mechanisms of autoimmunity

Factors contributing to

autoimmunity Spectrum of autoimmune diseases

Principles of treatment

Immunologic Tolerance


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Immunologic Tolerance

The unresponsiveness of the immune

system to self-antigens.



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Mechanisms that prevent immune

response to self antigens.



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Central

Negative selection T cells in the thymus

B cells in the bone marrow

PheripheralT cells

Functional unresponsiveness (Anergy)

Death of the effector cell (apoptosis)B cells

High concentration of self antigens in

peripheral lymphoid tissues become


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Regulatory T cell


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Regulatory T cell

CD4+CD25+ T cells

Maintains tolerance to self-antigens


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Autoimmune disease


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A disease caused by tissue damageresulting from a breakdown of

self-tolerance mechanisms.

Autoimmune diseases can be

organ-specific or systemic.



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y A defect in the mechanisms of self-tolerance

Molecular mimicry Eg; a cross-reactive antigen between heart muscle and

Group A Streptococcipredisposes to the development of

rheumatic fever

Modification of cell surface by microbes and drugs

(hapten-like manner) Drug-induced autoimmune haemolytic anaemia

Thrombocytopenia following viral infections

Presence of self reactive T cell in peripheral blood

Extrathymic T cell development Failure of negative selection

AIRE gene defect



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Polyclonal activation via microbial

antigens

Eg; endotoxin and EBV

Availability of normally sequestered selfantigens

Eg; lens of eye, central nervous system,

thyroid and testes Dysregulation of idiotype network

Eg; antibodies to insulin, TSH and

acetylcholine receptors



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autoimmunity

Age

Higher incidence in aged population Less stringent immune regulation by the ageing

immune system

Gender

Women have a greater risk than in men Neuroendocrine system influence

Male:Female SLE 10:1 Graves disease 7:1

Ankylosing spondylitis is almost exclusively amale disease



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autoimmunity

Infections

Eg; EBV, Mycoplasma, Streptococci,Borrelia burgdoferi(Lyme arthritis) and

malaria

Drugs

Eg; Procainamide (10% develop SLE likesyndrome)

Immunodeficiency

Eg: C2, C4, C5, C8 & IgA deficiency



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autoimmunity Genetic factors

Disease HLA Risk

Ankylosing spondylitis B27 90

Reiters disease B27 36SLE DR3 15

Myasthenia gravis DR3 2.5

IDDM DR3/DR4 25

Psoriasis DR4 14

Multiple sclerosis DR2 5

Rheumatoid arthritis DR4 4

Spectrum of autoimmune

diseases


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diseases

Organ specific Addisions disease - Adrenalcortex

Autoimmune haemolytic anaemia

Graves disease - TSH receptors Guillain-Barre syndrome - Peripheral

nerves

Hashimotos thyroiditis - Thyroid

peroxidase IDDM - F cells in

pancrease

PBC - pyruvate

deh dro enase



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diseases Several organs affected

Goodpastures syndrome

Basement membrane of kidney and lung

Polyendocrine Multiple endocrine organs

A group of cells affected

Autoimmune haemolytic anaemia Autoimmune thrombocytopenia


diseases


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diseases Systemic

Ankylosing spondylitis - vertebral

Chronic active hepatitis - DNA

Rheumatoid arthritis - IgG

(Rheumatoid factor) Scleroderma - nuclei &

centromeres

SLE - dsDNA

Wegerners granulomatosis Cytoplasm ofthe neutrophils

PAN - Cytoplasm of the neutrophils

Antiphospholipid syndrome

Principles of treatment


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Metabolic control

Graves disease Pernicious anaemia

Immune modulators NSAID

SAID Immunosuppressive cytotoxic drugs

Removal of offending antibodies or immunecomplexes - plasmapheresis

Surgical Thymectomy & Splenectomy

Screen for associated disorders

Objectives


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Define tolerance


Define autoimmunity and

autoimmune disease



autoimmunity Spectrum of autoimmune diseases


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Immunofluorescence technique

ANA


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Diagnostic,prognostic &

monitoring

Anti ds-DNA


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Anti ds DNA

SLE >90%


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Ankylosing spondylitis


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Achilles tendonitis in seronegative arthropathy

Oral ulceration in Behcets disease


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Circinate balanitis in Reiters disease


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Immunology for Sx Dd