Vaso-active intestinal peptide: a neurotransmitter which reduces human NK cell activity and increases Ig synthesis

The effect of vaso-active intestinal peptide (VIP) on natural killer (NK) cell activity and immunoglobulin synthesis in vitro has been studied. At a concentration of 10(-6)M, VIP significantly inhibited the NK cell activity of normal human peripheral blood mononuclear cells (PBMC) on K562 target cells. The concentration of IgG, IgA and IgM in the supernatants of pokeweed mitogen-stimulated PBMC was increased when VIP was added at the beginning of the culture period. It is possible that VIP may influence immune responses in the intestinal tract, where it is a neurotransmitter and is found in high concentrations.