The effect of thiols on immunologic release of slow reacting substance of anaphylaxis. I. Human lung.

Preincubation of human lung fragments with cysteine for 2.5 to 5.0 min resulted in dose-dependent, selective enhancement of the antigen-induced or anti-IgE-induced formation and release of slow reacting substance of anaphylaxis (SRS-A). Comparable effects were observed with sodium sulfide and thioglycolate but not with other more potent reducing agents or metabolites of cysteine. Sulfhydryl alkylated derivatives of cysteine were ineffective. The effects observed with the active thiols were easily reversed and could not be attributed to an action in the bioassay or on SRS-A itself. The physicochemical characteristics of the contractile activity were identical to those described for SRS-A.