7.5AutoimmuneDiseases

8/11/2019 7.5AutoimmuneDiseases

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Section 4 Autoimmune Diseases


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1. Definition:

An immune reaction against self-

antigens is the cause of certain

diseases in human.


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2. Mechanism

(1) Alteration of self-proteins (modification

of the molecule)

Partial degradation of autoantigens.

Complexing of self-antigens with drugs

or micro-organisms.

(2) Hidden antigens exposure


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(3) Cross-reactions (molecular mimicry)

Antibodies to streptococcal antigens may

react with constituents of cardiac muscle or

connective tissue in rheumatic fever.Rabies vaccine may rise to encephalitis


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(4) Breakdown of tolerance

Bypass of helper T cell tolerance

Imbalance of suppressor-helper T cell

function

Geneic fators

Emergence of a sequestered antigen

Polyclonal lymphocyte activation


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3. Classification

(1) Systemic autoimmune diseases

Systemic lupus erythematosus (SLE)

a. Definition:It is the classic prototype

of the multisystem disease ofautoimmune origin.


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Model for the pathogenesis of systemic lupus erythematosus. .(From Robbins Basic Pathology ,2003


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Lupus nephritis. There are two focal necrotizing lesions at 11 and

2 oclock. (H&E stain.) (Dr. Helmut Rennke)

(From Robbins Basic Pathology ,2003


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Immunofluorescence micrograph stained with fluorescent anti-IgG from a patient

with diffuse proliferative lupus nephritis. One complete glomerulus and part of

another one are seen. Note the mesangial and capillary wall deposits of IgG. (Dr.

Helmut Rennke) (From Robbins Basic Pathology ,2003


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Lupus nephritis showing a glomerulus with several wire loop lesions

representing extensive subendothelial deposits of immune complexes. (Periodic

acid-Schiff [PAS] stain.) (Dr. Helmut Rennke)



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Systemic lupus erythematosus involving the skin. A, An H&E-stained section

shows liquefactive degeneration of the basal layer of the epidermis and edemaat the dermoepidermal junction. (Dr. Jag Bhawan) B, An immunofluorescence

micrograph stained for IgG reveals deposits of immunoglobulin along the

dermoepidermal junction. (Dr. Richard Sontheimer)



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Libman-Sacks endocarditis of the

mitral valve in lupus

erythematosus. The vegetations

attached to the margin of thethickened valve leaflet are easily

seen. (Dr. Fred Schoen)



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b. Characteristics

(i) Immunologically, the disease involves abewildering array of auto-antibodies,particularly antinuclear antibodies (ANAs).

(ii) Anatomically, all sites of involment have incommon vascular lesions with fibrinoiddeposits.

(iii) Clinically, it is an unpredictable remitting,relapsing disease of acute or insidious in thebody, but principally affects the skin, kidneys,serosal membranes, joints and heart


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Sjogrenssyndrome

Definition:It is a clinicopathologic entitycharacterized by dry eyes and dry mouth

resulting from immunologically mediated

destruction of the lacrimal and salivaryglands.


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Sjogrens syndrome. A, Enlargement of the salivary gland. (Dr.Richard Sontheimer). B, The histologic view shows intense

lymphocytic and plasma cell infiltration with ductal epithelial

hyperplasia. (Dr. Dennis Burns) (From Robbins Basic Pathology ,2003


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Scleroderma(

Rheumatoid arthritis

Polymyositis

Polyarteritis nodosa


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The extensive subcutaneous fibrosis has virtually immobilized the

fingers, creating a clawlike flexion deformity. Loss of blood supply

has led to cutaneous ulcerations. (Dr. Richard Sontheimer)



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Note the rash affecting the eyelids. B, Dermatomyositis. Thehistologic appearance of muscle shows perifascicular inflammation

and atrophy. C, Inclusion body myositis showing a vacuole within a

myocyte. (Dr. Dennis Burns) (From Robbins Basic Pathology ,2003


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(2) Organ-specific diseases

Hashimotos disease (chronic lymphocytic

thyroiditis)

Gravessdisease

Goodpasturessyndrome

Insulin-dependent diabetes mellitus

Primary billiary cirrhosis


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Chronic ulcerative colitis

Malignant pernicious anaemia with

chronic atrophic gastritis

Chronic active hepatitis

Myasthenia gravis


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Slide 26.8Hyperthyroidism (Offered by Prof.Orr


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Hashimotos thyroiditis


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