To produce an allergic reaction in Type I hypersensitivity, the antigen
A) must bind to mast cells.
B) must bind to free IgE molecules.
C) must just bind to IgE on mast cells.
D) must bind to two neighboring IgE molecules on mast cells, crosslinking them.
E) must bind to two neighboring IgM molecules on mast cells, crosslinking them.

Question

Quizplus · Accepted Answer

In Type I hypersensitivity, the antigen must bind to two neighboring IgE molecules on mast cells, crosslinking them. This crosslinking triggers the release of histamine and other mediators, leading to an allergic reaction. Binding to free IgE molecules or just IgE on mast cells alone is not sufficient to cause the same reaction. Binding to IgM molecules on mast cells is unlikely as IgM is not typically involved in Type I hypersensitivity.

To Produce an Allergic Reaction in Type I Hypersensitivity, the Antigen