Effects of two neuropeptides, somatoliberin (GRF) and corticoliberin (CRF), on human lymphocyte natural killer activity.

The effect of corticoliberin (CRF) and somatoliberin (GRF) on the natural killer (NK) activity of human peripheral blood lymphocytes was investigated. NK activity was estimated by means of the radioactive chromium (51Cr) assay in which human leukemia K 562 cells serve as targets. Exposure of human lymphocytes (effector cells) to 10(-6) to 10(-10) M concentrations of CRF inhibited NK activity. NK activity was also suppressed by the same concentrations of GRF, but only when an effector:target cell ratio of 40:1 was used. In contrast, at effector:target ratios of 20:1 and 10:1, stimulatory effects of GRF were observed.