Immune Disorders Flashcards
Define hypersensitivity
inappropriate or exaggerated immune response
Define Type I (immediate) hypersensitivity
-quick reaction, 2-30 mins
-T-dependent B cell activation starts the sensitization process
-plasma cells produce IgE against the allergen
-IgE attaches to mast cells, basophils, and eosinophils
-subsequent exposure to the allergen results in the degranulation of mast cells, basophils, and eosinophils and inflammatory response
-can be systemic or localized
How are Type I hypersensitivities diagnosed?
Skin prick test
Define Type II hypersensitivity
-antibodies and complement lyse target cells
-happens in 5-12 hours
-antigens are located on the surface of a cell or tissue (incompatibility of blood cells)
-results in cell lysis
-activation of complement system via IgG or IgM
Define Type III immune (complex-mediated) hypersensitivity
-nonphagocytized complexes of antibodies and antigens trigger complement activation leading to inflammation, and causes neutrophils to release damaging enzymes.
-3-8 hour onset
-antigens that activate it are soluble
-complement and a particular ration of antibody to antigen are key
-result of viral, protozoa, and bacterial infections
-chemotaxis attracts neutrophils which degranulate and cause damage in blood cells
Examples of Type 1 hypersensitivities
food/seasonal allergies/environmental allergens
Examples of Type 2 hypersensitivities
transfusions and Rh incompatibilities, drug-induced cytotoxicity
Examples of Type 3 hypersensitivities
-pneumonitis, glomerulonephritis, and arthritis
-systemic lupus erythematosus and rheumotoid arthritis
Define type IV (delayed) hypersensitivity
-onset in 1-2 days
-previous sensitization results in T cell and macrophage migration towards antigen
-delayed hypersensitivity cells and memory T cells are involved.
Examples of Type IV hypersensitivity
PPD test for TB and allergic contact dermatitis (poison oak), graft rejection, and multiple sclerosis
Distinguish between systemic and localized reactions.
localized in one area
systemic is body-wide
Which types of cells degranulate with Type I hypersensitivities? Which chemical mediator (cytokine) plays a large role?
Mast cells, basophils and eosinophils
histamine
Describe blood incompatibilities. Which type of hypersensitivity does this correspond to?
Incompatibility between antigens on RBC and antibodies produced or Rh factor.
Type II
Describe the factors that lead to hemolytic diseases of the newborn (aka erythroblastosis fetalis).
Rh- mother sensitived to Rh+ blood during first pregnancy. In second pregnancy if baby is Rh+, IgG will cross placenta and attack blood of newborn.
Describe the role that memory T cells play in Type IV hypersensitivity.
Retain memory of antigen and become sensitized.
Distinguish between allografts, autografts, and xenografts.
Allograft- transplanting organs or tissue within same species
Autograft- tissue transplant from one part of body to another on same person
xenograft- transplanting tissue/organs between different species
Define privileged sites and give examples.
Less likely to reject tissue because of lack of blood supply/lymphatic vessels or contain a high amount of immunosuppressant molecules
Brain, cornea, testes, uterus, and thymus
Describe MHC typing
donor-receipiant match. Looking for a compatible match between MHC auto-antigens, especially those on white blood cells.
corticosteroids/glucocorticoids
inhibits the inflammatory response by inhibiting prostaglandin and leukotrine release and also suppresses T cell production.
ex. prednisone, cortisone, dexamethasone
cytotoxic drugs
prevent mitosis and cytokinesis. Prevent the manufacture of precursors for DNA replication or nucleic acids
ex. methotrexate and azathioprine
cyclosporine
Inhibit T cell function and prevents the production of interleukins. Given in combo with prednisone to prevent graft rejection
lymphocyte-depleting therapies
Antibodies destroy activated T cells (anti-lymphocyte globulin) or monoclonal antibodies that are specific for the receptor for IL-2 found on T cells.
Define autoimmune disease and give examples.
Body fails to distinguish between self and non self and attacks own cells
grave’s disease, diabetes type 1, rheumatoid arthritis, Chron’s disease
Distinguish between primary and secondary immunodeficiency diseases.
Primary- genetic and present at birth (SCID)
Secondary- acquired due to environment or immunosuppressant drugs, or microbes
Describe some opportunistic infections that are associated with AIDS.
pneumonia, Salmonella infection, candidiasis, toxoplasmosis, and tuberculosis (TB)
Describe the characteristics of HIV and its mechanisms of pathogenicity.
-enveloped SSRNA in the retroviridae family and lentivirus genus
-RNA converted to DNA through reverse transcriptase and incorporated into host cell
