Enhanced superoxide production by rat alveolar macrophages stimulated in vitro with biological response modifiers.

The kinetics of superoxide release and the effects of several biological response modifiers (BRM) on superoxide release from rat pulmonary alveolar macrophages (AM) have been studied. These cells produced superoxide anion both spontaneously and in response to phorbol myristate acetate (PMA) in a dose-related manner. The response to PMA peaked in approximately 2 hr and maintained plateau levels for an additional 2-3 hr before subsiding. Pretreatment of the macrophages in vitro with a number of immunostimulants enhanced the production of superoxide above that of controls. The release of superoxide in response to the immunostimulants was a slow phenomenon that took place over a 3-5 hr time period. Lymphokine-containing supernatants from concanavalin A (con A)-stimulated rat spleen cells (LK-Sup), murine recombinant gamma interferon (rMuIFN-gamma), nigeran, and muramyl dipeptide (MDP) enhanced this response in a dose-related manner. Poly I:C and Salmonella typhosa lipopolysaccharide (LPS) stimulated rat alveolar macrophages at low but not high concentrations. In contrast to the alveolar macrophages, rat peritoneal exudate cells were not activated by immunostimulants to produce increased amounts of superoxide.