The following is a summary of “Differential mast cell mediators in systemic mastocytosis and hereditary α-tryptasemia,” published in the November 2022 issue of Allergy and Clinical Immunology by Giannetti, et al.

Mast cell activation symptoms are frequently seen in patients with systemic mastocytosis and are connected to increased urine mast cell mediator metabolite concentrations. Mast cell activation symptoms may be observed in hereditary α-tryptasemia (HαT) patients. It was unknown if the levels of mast cell mediators were increased in the patient population. For a study, researchers sought to ascertain if urinary mediator levels in individuals with HαT and symptoms of mast cell activation were raised and to contrast those levels with those in patients with systemic mastocytosis.

They looked back at the mast cell mediators in 23 healthy controls, 63 patients with a confirmed diagnosis of indolent systemic mastocytosis (ISM), and 20 patients with a confirmed diagnosis of HαT. For the examination of mast cell activation disorders, all patients were sent to the Brigham and Women’s Hospital Mastocytosis Center or the Mayo Clinic.

The average age of the population was 53.8 years old, with 85.7% being female. Those with ISM had an average baseline blood tryptase level that was considerably higher than patients with HαT (65.9 vs. 19.3 ng/mL [P< .01]). Patients with ISM demonstrated statistically significant increases in urine N-methylhistamine (P <.01) and 2,3-dinor-11β-prostaglandin F2α (P< .05) levels compared to those with HT.

Mast cell urine metabolites were not elevated in patients with symptomatic HαT, indicating that mediators generated from granules and membranes may not be the cause of symptoms in HαT.