Type I hypersensitivity includes all of the following except:: (A) Autoimmune hemolytic anemia, (B) Anaphylaxis, (C) Extrinsic asthma, (D) Hay fever
Answer is A. Ans. is 'a' i.e., Autoimmune hemolytic anemia (Ref: Ananthanarayan, 9th/e, p. 162 and 8th/e, p. 162)* Autoimmune hemolytic anemia is type II HSN.* In type II Hypersensitivity reaction (Ab mediated) various mechanisms involves up: (1) Opsonization, complement and Fc receptor mediated phagocytosis (C3b acts as opsonin). (2) Complement and Fc receptor mediated inflammation (C5a acts as chemokine for neutrophil and monocyte. (3) Antibody mediated cellular dysfunction.