Immunoregulatory effects of neuropeptides. Stimulation of interleukin-2 production by substance p.

Substance P (SP), a tachykinin neuropeptide, has been previously reported to stimulate T cell proliferation, and SP receptors have been identified on subpopulations of T lymphocytes. The effect of SP on the interleukin-2 (IL-2) production has been investigated by using the murine EL-4.IL-2 and LBRM-T6G T cell lines. SP synergized with phorbol 12-myristate 13-acetate (PMA) in a dose-dependent manner to induce IL-2 production. The generated interleukin was identified as IL-2 by neutralization with a specific anti-murine IL-2 monoclonal antibody. The effect of SP was specific, since spantide and physalaemin which have affinity for SP receptors inhibited the generation of IL-2 by SP. These results provide additional evidence for the immunoregulatory role of neuropeptides, and suggest that the immunostimulatory action of SP could be mediated, at least in part, through the upregulation of IL-2 expression.