Inactivation by alveolar macrophages of slow-reacting substance of anaphylaxis released from pig lung cells.

The influence of alveolar macrophages on the release of slow-reacting substance of anaphylaxis (SRA-A) and histamine from dispersed pig lung cells was studied. The addition of alveolar macrophages to lung cells (1:3) decreased SRS-A release by 62% +/- 7% without a significant decrease in histamine release. Increased numbers of alveolar macrophages (1:1) decreased both SRS-A release (by 90% +/- 5%) and to a lesser extent histamine release (by 59% +/- 18%). The decrease in released SRS-A was not caused by prostaglandin release from macrophages, and kinetic data indicated that in contrast to histamine the decrease was predominantly the result of SRS-A inactivation rather than inhibition of its release. When alveolar macrophages were incubated with SRS-A, inactivation (191 units/10(7) cells/30 min) was confirmed. SRS inactivation was not reproduced by glutaraldehyde-treated macrophages or by granulocyte and mononuclear populations obtained from peripheral blood. Alveolar macrophages may limit the consequences of SRS-A release in the peripheral air spaces.