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10 Cards in this Set
- Front
- Back
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immunopathology
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process by which the host's cells/tissues are injured through the host's immune response to a stimulus
- innocent bystander - attacks self targets |
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Type I hypersensitivity
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(anaphylactic type)
- rapidly evolving immune reaction - occurs within minutes of Ag/Ab bound to sensitized cell - IgE mediated - IgE attaches to mast cells--> release mediators |
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mast cell mediators
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1. smooth muscle contraction, increased blood vessel leakage, increase secretion (caused by histamine)
2. attract neutrophils 3. enzymes |
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Forms of Type I hypersensitivity
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1. local (seasonal allergies)
2. systemic: anaphylaxis --> involves bronchiole constriction (respiratory distress), laryngeal obstruction, pulmonary edema, shock and death within minutes |
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Type II hypersensitivity
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(cytotoxic type)
- antibodies directed toward antigens present on cells or other tissue components cause cell/tissue damage |
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mechanisms of Type II hypersensitivity
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1. tissue damage: Abs and complement
ex: transfusion rxns and Goodpasture disease 2. natural killer lymphocytes ex: neoplastic cell killing 3. Ab binding impairs function ex: myasthenia gravis and Grave's disease |
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Type III hypersensitivity
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(immune complex type)
- Ag-Ab complexes deposit in tissues leading to localize inflammation and tissue damage - often seen in glomerular capillaries in kidney, synovium of joints, or dermal capillaries of skin ex:post-streptococcal glomerulonephritis |
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mechanism of Type III
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- activate complement
- neutrophils are attracted - may release proteolytic enzymes - attack surrounding tissues |
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Type IV hypersensitivity
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(cell mediated type)
- cell mediated tissue damage caused by sensitized T-lymphocytes ex: granuloma formation, rejection of transplanted organ |
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forms of Type IV hypersensitivity
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1. delayed type: mediated by CD$ T cells reacting with cells
2. Direct toxicity: sensitized CD8 T cells destroy antigen-bearing target cells |
