Polymorphonuclear leukocyte regulation of lymphocyte proliferation and differentiation

The polymorphonuclear neutrophil (PMN) regulates in vivo and in vitro immune responses. We report that the immunoenhancing properties of PMN culture supernatants from PMN recruited by the bacterium Actinomyces viscosus (AV) show its exclusive effects on the T cell lymphocyte population. A study of the effect of PMN supernatants on normal Balb/c splenocytes to T and B cell mitogens showed enhancing effects on T cell mitogens, but no effect on B cell mitogen responses when compared to a control. Adherent cells (macrophages) were not required for the enhancing effect, indicating that the supernatant worked directly on the T cell. Proliferation of El-4, a Lyt-1.2 positive lymphoma helper cell, was directly affected by these supernatants. Functionally, T cell-dependent plaque-forming cell responses to sheep red blood cells (SRBC) were enhanced. The polyclonal, T cell-independent plaque-forming cell response was unaffected when generated with LPS as assayed with Protein-A-SRBC. These results indicate that PMN supernatants from cells recruited by AV act on a helper T cell population to enhance both proliferation and differentiation in lymphocyte populations. These interactions provide insight into local inflammatory responses of PMN-lymphocyte infiltration with altered cell-mediated immunity.