Neuropeptides and Natural Killer Cell Activity

Abstract

Various neuropeptides are present in human peripheral blood and may bind to immune competent cells via stereospecific membrane receptors. The aim of the present study has been to determine the effects of three synthetic neuropeptides: corticoliberin (CRF1–41), somatoliberin (GRF1–44) and somatostatin (SRIF1–14) on natural killer (NK) activity of human peripheral blood lymphocytes. The NK activity was estimated by means of radioactive chromium 51Cr assay with the use of human leukemic K 562 cells as targets. The previous exposure of human lymphocytes (effector cells) to CRF at concentrations of 10-10 – 10-6 M resulted in inhibition of NK cells activity. The NK activity was also suppressed by the same concentration of GRF, but only if effector: target cells ratio equal 40:1 was used. On the other hand, the NK activity, expressed as % of specific cytolysis, was increased after the exposure of the effector cells to SRIF in concentrations of 10-8 and 10-6 M at all target: effector cells ratios tested. We conclude that neuropeptides, circulating in the peripheral blood, may have some physiological role in the modulation of human lymphocyte NK activity.