MIGRATION OF DISTINCT SUBSETS OF CD8(+) 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 (>95%) SGF1(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 migate through allogeneic endothelial cells and would thus be likely to be recruited to sites of antigen challenge.