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What is Wheal and Flare reaction is which type of Hypersensitivity? and explain in detail?
ANSWER: (A) Type IREF: APPENDIX-21 below for "HYPERSENSITIVITY REACTIONS"Wheal-and-flare reaction: (Stedman s Medical Dictionary)The characteristic immediate reaction to an injected allergen in a skin test, in which an irregular blanched wheal, appears surrounded by an area of redness. Also called as wheal and erythema reaction. APPENDIX - 21Hypersessitivity ReactionsTYPE 1:Allergy/Atopy/' AnaphylaxisTrue AnaphylaxisFree Ag - fixed IgE (on mast cell)Wheal and Flare reaction Casoni s test, anaphylaxis, prusnitz kunster reaction, Theobald smith phenomenon, Schultz dale phenomenon, Atopic dermatitis, Pseudoanaphylaxis (Anaphylactoid reaction)Free Ag - direct degranulation of mast cell (not IgE mediated)Iodine-containing radio contrast (me), aspirin and muscle reiaxants, morphineTYPE 2:AntibodydependentcytotoxichypersensitivityFree Ab - fixed AgIgM IgG/ComplementmediatedAutoimmune hemolytic anemiaHemolytic disease of the newborn (erythroblastosis fetalis)Autoimmune thrombocytopenic purpuraGoodpasture's syndrome: Pemphigus vulgarisBullous pemphigoid; Acute rheumatic feverPernicious anemia: Myasthenia gravis; Graves' diseaseADCC- antibody- dependent cell-mediated cytotoxicityAcute & chronic transplant rejectionTYPE 3: Immune complexFree Ag+ Free Ab - Immune complexSerum sicknessArthus reactionSystemic lupus erythematosus (SLE)Immunoglobulin therapyHyperacute graft rejectionAcute necrotizing vasculitisPolyarteritis nodosa Post streptococcal glomerulonephritisShick s testTYPE 4: Delayedhypersensitivity,cell-mediated,antibody-independentAg -T cell mediated (CD4/CD8)Delayed: CD4mediated .contact & tuberculin types with in 72 hours, Granulomatous type; 21-28 days]Contact dermatitis; Mantoux (tuberculin) testLepromin testChronic transplant rejectionMultiple sclerosisPhlyctenular keratoconjunctivitisJones mote reaction (cutaneous basophilic hypersensitivity)Direct cell toxicity:CD8 mediatedPerforin dependent killingFas-FasL dependent killingAlso know: Graft rejection is type 4 hypersensitivity unless type is provided. (Most of the MCQ guides have quoted this falsely)HyperacuteType 3AcuteType 4 >2 (both if provided)Acute cellular rejection = type 4 (better prognosis) Acute vascular rejection = type 2ChronicType 2