Regulation of naïve fetal T-cell migration by the chemokines Exodus-2 and Exodus-3.

We and other workers have recently isolated three novel CC chemokines termed Exodus-1/LARC/Mip-3alpha, Exodus-2/6Ckine/SLC/TCA4, and Exodus-3/Mip-3beta/CKbeta11/ELC. These chemokines share an amino terminal Asp-Cys-Cys-Leu sequence, unique among all chemokines. They also selectively regulate migration of adult T cells. Indeed, there is evidence that Exodus-2 and -3 are critical for adult T-cell adhesion to high endothelial venules in lymph nodes, a rate-limiting step for T-cell trafficking through nodal tissue. Less is known of the factors controlling migration of naïve human fetal T cells. We tested whether these chemokines could regulate chemotaxis in cord blood T-cell populations, and compared that efficacy with normal peripheral blood adult T cells. The findings indicated that naive CD45RA+ cord blood T-cell migration is stimulated by Exodus-2 and -3, and CD4+ cord blood T cells are attracted preferentially by Exodus-2 or -3 as compared with CD8+. Exodus-2 and -3 are likely to be critical in regulating the flux of naive CD4 + fetal T-cell population of secondary lymphoid tissue.