DIFFERENTIAL REACTIVITY OF HUMAN BRONCHOALVEOLAR LAVAGE MAST-CELLS TOSUBSTANCE-P

Substance P (SP) stimulates human skin and rodent mast cells. Since ne uropeptide-mediated reflexes may be important in asthma, the ability o f SP to stimulate human mast cells obtained at bronchoalveolar lavage (BAL) was examined. Routine BAL (n = 22) samples were obtained and his tamine release experiments performed in a standard manner. Spontaneous histamine release was bimodally distributed (Group A, high spontaneou s release/Group B, normal spontaneous release). Further, Group A had s ignificantly elevated corrected SP-induced histamine release compared to Group B but the corrected calcium ionophore A23187-induced response s were similar. No differences were found in clinical history, age, la vage return or total cell numbers between groups. However, differentia l cell counts revealed significantly elevated mast cell numbers in Gro up A providing further evidence for altered mast cell responsivity ass ociated with mast cell hyperplasia. In asthma, BAL mast cells have inc reased spontaneous and stimulated secretory responses; thus, in asthma SP may also stimulate pulmonary mast cells.