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Vasoactive intestinal peptide (VIP), a 28-amino acid peptide of the glucagon-secretin family, has been reported to have significant immunoregulatory properties. In the present study, we demonstrate that VIP has potent chemotactic effects on T lymphocytes. At concentrations of between 10(-8) and 10(-9) M, VIP stimulated significant in vitro chemotaxis of T lymphocytes from both CD4+ and CD8+ subsets. VIP produced more potent chemotactic effects on unstimulated T cells than on anti-CD3-activated cells. Following anti-CD3 activation, binding of 125I-labeled VIP to T cells was reduced and this correlated with a reduction in receptor number without any change in affinity. Preincubation of unstimulated T cells with VIP produced increases in adhesion to ICAM and VCAM integrins. In addition, VIP pretreatment significantly increased unstimulated T cell adhesion to the extracellular matrix protein fibronectin. However, VIP induced less binding of activated T cells to fibronectin. Taken together these results suggest that VIP is a potent chemoattractant and stimulant of adhesion for T lymphocytes. In contrast to chemokines that are more active on stimulated T cells, such as RANTES, this neuropeptide preferentially targets unactivated T cells, suggesting that it may play a greater role in homing and distribution of lymphocytes.
Johnston et al. (Mon,) studied this question.