Polymorphonuclear leukocyte activation by a synthetic muramyl dipeptide analog.

N alpha-(N-Acetylmuramyl-L-alanyl-D-isoglutaminyl)-N epsilon -stearoyl-L-lysine, a synthetic derivative of muramyl dipeptide, stimulated the chemotactic mobility, phagocytic activity, and superoxide anion (O2-) productivity of peritoneal polymorphonuclear cells in mice. The chemotactic mobility of both cells preincubated with the adjuvant in vitro and those derived from the mice previously treated with the adjuvant was significantly enhanced. The phagocytic activity of cells preincubated in vitro with the adjuvant was also enhanced transiently, and that of the cells derived from the mice treated subcutaneously with the adjuvant 24 h before intraperitoneal inoculation with Escherichia coli was significantly greater than that of cells from the mice given phosphate-buffered saline instead of the adjuvant. The release of O2- from the cells derived from the adjuvant-treated mice was also greater than that from the cells of untreated control mice. However, the exposure of the cells derived from untreated mice to the adjuvant in vitro did not stimulate O2- generation by the cells.