Stinging Hymenoptera and mastocytosis.

PURPOSE OF REVIEW: Patients suffering from mastocytosis are at risk for a particularly severe Hymenoptera sting anaphylaxis. The purpose of this review is to evaluate the current knowledge on pathophysiologic events, which might explain the specific risk of patients with mastocytosis.

RECENT FINDINGS: Mast cell products can neutralize major toxins of snake or bee venoms. beta-tryptase from mast cells is able to degrade allergens and IgE antibodies. Thus, mast cells and their mediators should protect patients from venom toxicity and should also lead to a decreased allergenicity. However, these theoretically beneficial effects of mast cells on downregulating allergic immediate type reactions are insufficient to protect patients with mastocytosis from severe anaphylaxis. In contrast, these patients are at an even higher risk. Many compounds of Hymenoptera venom can induce Fcepsilon receptor-independent mast cell degranulation. In the context of mast cell activation induced by Hymenoptera venom, FcepsilonRI-dependent stimulation of mast cells via bridging of specific IgE-antibodies may be of particular importance. Abundance and dysfunction of mast cells in patients with mastocytosis may explain a significant portion of the particularly high anaphylactic risk in patients with mastocytosis.

SUMMARY: The particular anaphylactic risk of patients with mastocytosis results from a variety of mechanisms. However, their individual contribution still needs further clarification.