IMMUNOLOGY

Detailed explanation-1: -During an allergic response IgE release from B-cells will bind to mast cells, blanketing the plasma membranes of these immune cells. Half a million IgE molecules coat the surface of mast cells, binding to the high-affinity IgE receptors (FcɛRI) on membranes with the Fc portion.

Detailed explanation-2: -C3a, C4a, and particularly C5a trigger the degranulation of mast cells and basophils, which release the vasoactive amines that cause the increased vascular permeability and smooth muscle contraction characteristic of inflammation.