[Characterization of slow reacting substance of anaphylaxis in asthmatic sputum].

Sputum from asthmatics contained a mediator similar to slow reacting substance of anaphylaxis (SRS-A), capable of inducing contraction of guinea pig ileum. This mediator possessed the major characteristics of SRS-A, including stability in both neutral and alkaline solutions, lability in boiling acidic solution, destruction by arylsulfatase, inhibition by FPL 55712 and resistance to diphenhy dramine . Thus, we proved that the "SRS-A like" mediator was in fact SRS-A. The activity of histamine in these patients' sputa could be inhibited only by diphenhydramine, but could not be altered by any of the other treatments noted above.