Identification of subsets of human T cells capable of enhanced transendothelial migration

A critical step in immunologically mediated inflammation is the migration of T cells between endothelial cells of postcapillary venules and into the tissues. To determine whether specific cells are capable of transendothelial migration, T cells that had migrated through endothelial monolayers were retrieved and analyzed. To accomplish this, human umbilical vein endothelial cells (EC) were cultured to confluence on collagen gels and incubated with human T cells. T cells that were nonadherent to the EC, those that bound to the endothelium, and cells that had migrated through the endothelial monolayer and into the collagen were individually harvested and characterized. After a 4-h incubation with EC, T cells distributed themselves such that 77 ± 2% were nonadherent, 13 ± 2% were bound to EC, and 10 ± 1% had migrated into the collagen. The CD4⁺ T cells that had migrated into the collagen were predominantly CD29^bright/CD45RO^bright and CD45RA^-. CD8⁺ T cells demonstrated a greater transendothelial migratory capacity than the CD4⁺ T cells. The migrated CDS⁺ T cells were mainly CD29^bright but CD45RA⁺. Additional phenotypic analysis of the migrating cells indicated that they contained fewer cells that expressed L-selectin. Moreover the surface expression of CD7 was less dense in the T cells that had migrated than in the nonadherent T cells. Finally the T cells that migrated were not enriched for CD45RB^dim T cells. Prolonging the incubation with EC to 36 h increased the number of T cells that migrated but did not alter the predominance of CD29^bright T cells in the migrated population. Stimulation of EC with IL-1 or IFN-γ also increased the number of adherent and migrating T cells, respectively, but did not alter the phenotype of the migrating cells. These results indicate that the capacity for transendothelial migration is an intrinsic ability of certain subpopulations of T cells and is related to their stage of differentiation as identified by their surface phenotype.