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 F_2α (11β-PGF_2α) excretion. LTE₄ excretion is increased in patients with systemic mastocytosis and potentially contributes to clinical symptoms.