Type I hypersensitivity reaction is mediated by:: (A) IgG, (B) IgM, (C) IgD, (D) IgE
Answer is D. In immediate hypersensitivity (type I hypersensitivity)- the injury is caused by TH2 cells, IgE antibodies, and mast cells and other leukocytes. Mast cells release mediators that act on vessels and smooth muscle and pro-inflammatory cytokines that recruit inflammatory cells.