Modulation of the Proliferative Response of Murine Peyer's Patch Lymphocytes by Different Peptides: CCK-8, CGRP, CCK-PZ and VIP. Preliminary Results

Abstract

There is evidence of an innervation of the mucosal immune system by peptidergic fibers. The modulation of the mitogenic response of the murine Peyer's patch lymphocytes by several peptides present in the gastrointestinal tract, namely, the carboxy-terminal octapeptide of cholecystokinin (CCK-8), the entire molecule cholecystokinin-pancreozymin (CCK-PZ), the calcitonin gene-related peptide (CGRP) and the vasoactive intestinal peptide (VIP), was studied. The proliferative response of the T lymphocytes induced by 2.5 μg/ml concanavaline A (Con A) was dose dependently inhibited by CGRP and VIP, with a maximal inhibition of 40% and 55% with 10−7M CGRP and VIP, respectively. On the contrary, CCK-PZ exerted a significant stimulatory effect, 48% increase in thymidine incorporation being observed with 62.5 mU/ml (Crick units) CCK-PZ. CCK-8 was found to have no effect on the T cell proliferation. None of the peptides tested were able to modify the mitogenic response of Peyer's patch B lymphocytes induced by 20 μg/ml lipopolysaccharide (LPS), except for CCK-PZ which induced a significant inhibition of the mitogenesis with a maximal effect of 45% inhibition at 500 mU/ml. These preliminary results show that CGRP, VIP and CCK-PZ can affect the murine Peyer's patch T and B lymphocyte response and suggest that they could be implicated in the modulation of the local immune response in the intestine.