Type 1 hypersensitivity reaction differs from type 2 hypersensitivity reaction being?: (A) Type 1 reaction is Ig E mediated, (B) Type 1 reaction is compliment mediated, (C) Type 1 reaction is involves opsonization, (D) All of the above
Answer is A. Ans. is 'a' i.e., Type 1 reaction is IgE mediated * Currently the most commonly used classification system of hypersensitivity is that of Gell and Coombs classification that divides the hypersensitivity into the following 4 types -1. Type I reactions (immediate hypersensitivity) - Involve immunoglobulin 'E' (IgE) mediated release of Histamine and other mediators from mast cells and basophils.2. Type II reactions (Antibody mediated) - Involve immunoglobulin G or Immunoglobulin M bound to cell surface antigen, with subsequent complement fixation.3. Type III reactions (Immune complex mediated) - involve circulating antigen-antibody complexes that deposit in postcapillary venules, with subsequent complement fixation.4. Type IV reactions (delayed hypersensitity, cell mediated) - Mediated by T cells.