Lymphocyte migration through cultured endothelial cell monolayers derived from the blood-retinal barrier

Lymphocyte migration across endothelial monolayers, derived from the rat blood-retinal barrier, was recorded in vitro using time-lapse video microscopy. Syngeneic lymphocytes were plated out onto endothelial cell monolayers for 4 hr and their surface motility and transmonolayer migration recorded and quantified. Under resting conditions lymphocytes, obtained from peripheral lymph nodes (PLN), were small, rounded and static with less than 5% migrating across the monolayer. Activation of the lymphocytes with concanavalin A (Con A) increased their size and surface motility on both interferon-gamma (IFN-gamma)-treated and resting endothelia, but did not alter the number migrating across the monolayer. Similar results were also found for phytohaemagglutinin (PHA)-activated lymphocytes. Interleukin-2 (IL-2)-dependent CD4+ T-cell lines specifically recognizing either retinal soluble antigen (S-Ag) or bovine serum albumin (BSA) exhibited significantly greater surface motility over the endothelial monolayers than the mitogen-activated PLN lymphocytes. By 4 hr, in excess of 50% of the T-cell line lymphocytes had migrated across the endothelial monolayer. Treatment of the endothelial cells with IFN-gamma caused a small, but not significant, increase in the level of T-cell line lymphocyte migration. These results suggest that the migration of lymphocytes across central nervous system-derived endothelia is primarily dependent upon the state and mode of lymphocyte activation.