Effect of the neuropeptides beta-MSH, neurotensin, NPY, PHI, somatostatin and substance P on proliferation of lymphocytes in vitro.

Various neuropeptides were tested in a wide dose range for an effect on lymphocyte-proliferation. The response of spleen cells to the mitogen phytohaemagglutinin (PHA) was stimulated by somatostatin in doses ranging from 10(-6) to 10(-18) M. The effect of somatostatin was only seen when the peptide was added at the start of incubation, indicating an effect on the inductive phase of mitogen stimulation. Weak stimulative effects were also seen of somatostatin (10(-6) M) on spontaneous proliferation of thymocytes and of beta-MSH on PHA-treated thymocytes and PHA-treated spleen cells when the peptide was added after 24 h of culture.