Increased leukotriene E4 excretion in systemic mastocytosis

Cysteinyl leukotrienes such as LTE4 are produced by mast cells, neutrophils, eosinophils, and macrophages. LTE4 levels have not been reported in systemic mastocytosis, a disorder with a large increase in mast cell numbers. Urinary LTE4 from patients referred for symptoms potentially due to mast cell degranulation or systemic mastocytosis was measured by a commercial cysteinyl leukotriene enzyme immunoassay kit. The diagnosis of systemic mastocytosis was established using current World Health Organization criteria. Compared with a control group of patients with various potential mast cell–related symptoms (e.g., “spells”), patients with systemic mastocytosis had a significant (P = .01) increase in urinary LTE4 excretion, whether expressed as LTE4 ng/g creatinine or as LTE4 ng/24 h. There was a moderate correlation of LTE4 ng/24 h with excretion of N-methyl histamine and serum tryptase but not with urinary 11β-prostaglandin F2α (11β-PGF2α) excretion. LTE4 excretion is increased in patients with systemic mastocytosis and potentially contributes to clinical symptoms.