Enhanced adhesion of rat neutrophils to Litomosoides carinii microfilariae in the presence of culture supernatants from mitogen-stimulated lymph node cells.

Microfilariae of the rat filarial parasite Litomosoides carinii are killed by normal rat neutrophils which adhere to them in the presence of antibody and complement. Adherence and killing were increased in the presence of the fluid from 48-hr cultures of Con A- or PHA-stimulated normal rat lymph node cells. Both normal and augmented binding were inhibited by cytochalasin B. The factor(s) responsible for increased binding was non-dialysable, susceptible to heat (56 degrees C, 30 min) and freezing and thawing. Its production was inhibited by cycloheximide. Pretreatment of neutrophils with stimulated culture supernatant for 3 hr, followed by washing, also augmented adherence. Similar pretreatment also enhanced phagocytosis of opsonized sheep erythrocytes and latex particles but did not increase candidacidal activity. These experiments suggest that cell-mediated immune reactions leading to lymphokine production may potentiate anti-filarial antibody-dependent cellular cytotoxicity and general phagocytosis by neutrophils.