TRANSDUCTION OF SPECIFIC-INHIBITION OF HUT-78 HUMAN T-CELL CHEMOTAXISBY TYPE-I VASOACTIVE-INTESTINAL-PEPTIDE RECEPTORS

The major immunoregulatory effects of vasoactive intestinal peptide (V IP) are mediated by structurally distinct types I (VIPR1) and II (VIPR 2) G protein-associated receptors on some T cells, B cells, and macrop hages. Identification of the separate immunologic activities of each t ype of VIPR has been complicated by the usual expression of only VIPR2 or of VIPR1 and VIPR2 together by most human T cells obtainable in su fficient number for functional analyses, The results of reverse-transc ription PCR, Western blot, and [I-125]VIP-binding studies have establi shed that HuT 78 cultured human lymphoma T cells bear a mean of 75,000 VIPR1s per cell with a mean K-d of 3.3 nM, which transduce mean maxim al increases in intracellular concentration of cAMP of 2.1-fold (ED(50 ) = 72 nM), but no VIPR2s, HuT 78 T cells, in contrast to T cells that express VIPR2, did not respond to VIP by chemotaxis through micropore filters without or with a top layer of basement membrane-like Matrige l, Matrix metalloproteinase (MMP)-dependent in situ cleavage of [H-3]t ype IV human collagen in the layer of Matrigel by HuT 78 T cells also was not stimulated by VIP. In contrast, IL-4 and TNF-alpha both stimul ated HuT 78 T cell chemotaxis and in situ MMP activity at respective o ptimal concentrations ranging from 3 x 10(-10) M to 3 x 10(-9) M and 1 0(-10) M to 3 x 10(-10) M. VIP inhibited significantly HUT 78 T cell c hemotaxis through Matrigel in response to both IL-4 and TNF-alpha, as a result of suppression of both chemotactic mobility, assessed by migr ation through micropore filters without Matrigel, and in situ MMP acti vity, The transduction of opposite effects of VIP on T cell migration through a model basement membrane by VIPR1 and VIPR2 suggests that the net chemotactic response of most T cells to VIP is determined by the VIPR2/VIPR1 ratio and that the predominant expression of VIPR1 would s tabilize T cell populations in lymphoid follicles and tissue infiltrat es.