A distinct biomolecular profile identifies monoclonal mast cell disorders in patients with idiopathic anaphylaxis

Abstract

Background

Clonal mast cell disorders are known to occur in a subset of patients with systemic reactions to Hymenoptera stings. This observation has prompted the question as to whether clonal mast cell disorders also occur in patients with idiopathic anaphylaxis (IA).

Objective

We sought to determine the prevalence of clonal mast cell disorders among patients with IA, criteria to identify those patients who require a bone marrow biopsy and whether the pathogenesis of IA involves a hyper-responsive mast cell compartment.

Methods

We prospectively enrolled patients with IA (≥3 episodes/yr) and who then underwent a medical evaluation that included a serum tryptase determination, allele-specific quantitative polymerase chain reaction (ASqPCR) for KIT D816V and a bone marrow examination. Mast cells were cultured from peripheral blood CD34+ cells and examined for releasibility following FcεRI aggregation.

Results

Clonal mast cell disease was diagnosed in 14% of patients referred with IA. ASqPCR for the KIT D816V mutation was a useful adjunct in helping identify those with systemic mastocytosis (SM) but not monoclonal mast cell activation syndrome (MMAS). A modified overall clonal prediction model was developed using clinical findings, a serum tryptase determination and ASqPCR. There was no evidence of a hyper-responsive mast cell phenotype in patients with IA.

Conclusion

Patients with clonal mast cell disease may present as idiopathic anaphylaxis. Distinct clinical and laboratory features may be used to select those patients more likely to have an underlying clonal mast cell disorder (MMAS or SM) and thus candidates for a bone marrow biopsy.