Migration of distinct subsets of CD8\u3csup\u3e+\u3c/sup\u3e blood T cells through endothelial cell monolayers in vitro

The immune response in many infections and to allografts is dependent on CD8+ cytotoxic T lymphocytes (CTL). Influx of CD8+ CTL from the blood has been documented during antigen challenge. We have previously found that a subset of CD8+ T cells from normal blood can migrate through endothelial cell monolayers in vitro. To further characterize migration-prone CD8+ T cells from normal blood, we examined the expression of CD28 and a restricted epitope of CD18/CD11a (S6F1), a CTL marker. Although normal blood CD8(bright+) T cells were heterogeneous in their expression of CD28, three populations could be identified (CD28(low), CD28(moderate), and CD28(high). CD8+ cells migrating across endothelial cell monolayers were enriched for CD8(bright+) CD28(high) cells and a subset of CD8(dim+) cells, which were CD28(high). Both adherent and migrating CD8+ cells were exclusively (\u3e95%) S6F1(high). There was also preferential adhesion and migration of CD8+ cells expressing the low molecular-weight form of the leukocyte common antigen, CD45RO. Cytokine activation of the endothelium did not significantly alter preferential migration of these subsets. These data suggest that certain subsets of CD8+ memory T cells in normal human blood are prone to, adhere to, and migrate through allogeneic endothelial cells and would thus be likely to be recruited to sites of antigen challenge