Macrophage-neutrophil interactions: contrasting effects of the monokines interleukin-1 and tumour necrosis factor (cachectin) on human neutrophil adherence.

Incubation of human neutrophils with recombinant human interleukin-1 alpha (IL-1 alpha) resulted in the suppression of neutrophil adherence. In contrast, similar treatment with recombinant human tumour necrosis factor-alpha (TNF alpha, cachectin) resulted in the enhancement of neutrophil adherence. These contrasting effects were noted as early as 5 min after incubation, and persisted for at least 60 min. Simultaneous addition of these two monokines resulted in intermediate values between suppression by IL-1 and enhancement by TNF alpha. The stimulatory effects of the chemotactic peptide FMLP and the phorbol ester PMA were ameliorated by IL-1 but augmented by TNF alpha. The effects of these monokines on neutrophil adherence were abolished by heating but not by polymyxin B treatment, showing that their modulatory properties were not mediated by endotoxin.