This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Antigen-antibody complex mediated hypersensitivity is - \nSelect and explain. \nA. Type -1 hypersensitivity, B. Type -2 hypersensitivity, C. Type -4 hypersensitivity, D. Type -3 hypersensitivity', 'role': 'user'}, {'content': 'Answer: D \nExplanation: a) Type I reactions (immediate hypersensitivity) → Involve immunoglobulin ‘E’(IgE) mediated\xa0release of Histamine and other mediators from mast cells and basophils.\nb) Type II reactions (Antibody-mediated) → Involve immunoglobulin G or Immunoglobulin\xa0M bound to cell surface antigen, with subsequent complement fixation.\nc) Type III reactions (Immune complex-mediated) → involve circulating antigen-antibody\xa0complexes that deposit in postcapillary venules, with subsequent complement fixation.\nd) Type IV reactions (delayed hypersensitivity\xa0cell-mediated) → Mediated by T-cells.', 'role': 'assistant'}]