03/15e Immunopathology I Flashcards
What is systemic lupus erythematosus?
A febrile, multisystem inflammatory disease that variably affects many organs, especially the skin, kidneys, serosal surfaces, joints, and heart
Clinical course is highly variable
What is the pathogenesis of SLE?
Autoantibodies develop against a variety of antigens, particularly nucleoproteins and nucleic acids, blood cells, and phospholipids
How do the antibodies of SLE cause disease? List two ways
By forming antigen-antibody complexes and depositing in the body, particularly in blood vessels, and activating complement
By binding to cells and causing lysis via complement- or antibody-mediated cytotoxicity
What are three possible causes of autoantibody production?
1) Intrinsic B cell defects
2) Excessive helper T cell activity
3) Deficient suppressor T cell activity
What is rheumatoid arthritis?
A systemic, chronic inflammatory disease that principally affects the joints, and causes severe, deforming, symmetric polyarthritis
Can involve other organs
What is the hypothesized pathogenesis of rheumatoid arthritis?
Activation of CD4 T cells, possibly by an infectious agent, lead to production of lymphokines
Lymphokines activate macrophages, other inflammatory cells, and B cells
This leads to inflammation, tissue destruction, and production of autoantibodies
What vessels are involved in hypersensitivity vasculitis?
Small vessels - venules, arterioles, capillaries
What are the clinical features of hypersensitivity vasculitis?
Skin lesions (common) - palpable purpura, macules, vesicles, necrosis, and ulceration Vascular lesions in other organs
By what three features can vasculitis syndromes be classified?
1) What type of vessels are affected
2) Distribution of affected vessels, i.e. what organs are affected
3) Histological and morphological features
What is the most common cause of hypersensitivity vasculitis?
Reactions to drugs and pathogens
What are the five steps of hypersensitivity pathogenesis?
1) Antibody response to exogenous antigen or autoantigen
2) Immune complex formation
3) Deposition of immune complexes in vessels, especially venules
4) Complement fixation and release of anaphylatoxins
5) Attraction of inflammatory cells and tissue destruction
What is the characteristic histology of hypersensitivity vasculitis?
Infiltration by neutrophils and neutrophil degeneration
Vessel wall necrosis in severe cases
Immune complex deposition (Ig components may vary)
What vessels are involved in temporal arteritis?
Elastic tissue-rich major arteries
What are the clinical features of temporal arteritis?
Severe headaches or facial pain, often unilateral
Visual disturbances
Constitutional symptoms - fever, fatigue, weight loss
Often associated with polymyalgia rheumatica
What are the two characteristic histologic patterns of temporal arteritis?
1) Granulomatous inflammation with multinucleate giant cells centered on the IEL
2) Mononuclear inflammatory infiltrate without giant cells and occasional fibrinoid necrosis
