The patient's anaphylactic reaction is determined to be mediated by antigen-specific IgE antibodies attached to high-affinity receptors on the surface of mast cells and basophils. Which of the following mechanisms is most likely to trigger vasoactive substance release by these cells?

Question

The patient's anaphylactic reaction is determined to be mediated by antigen-specific IgE antibodies attached to high-affinity receptors on the surface of mast cells and basophils.  Which of the following mechanisms is most likely to trigger vasoactive substance release by these cells?

Quizplus · Accepted Answer

Eductional Objective: The high-affinity IgE receptor (FcRI) is found on the surface of mast cells and basophils and normally binds the Fc portion of circulating IgE antibodies.  Cross-linking of multiple membrane-bound IgE antibodies by a multivalent antigen results in aggregation of the FcRI receptors, causing degranulation and the release of preformed mediators (eg, histamine, tryptase) that initiate an allergic response.

The Patient's Anaphylactic Reaction Is Determined to Be Mediated by Antigen-Specific