CHARACTERIZATION OF ADHERENT T-CELLS TO HUMAN ENDOTHELIAL-CELLS IN PATIENTS WITH HTLV-I-ASSOCIATED MYELOPATHY

To clarify the phenomenon of increased adherence of T cells to endothelial cells (EC) in patients with HTLV-I-associated myelopathy (HAM), we determined the surface markers and expression of lymphocyte function antigen-1 (LFA-1) in T cells adherent or nonadherent to EC. The percentage of activated or HLA-DR+ T cells and the expression of LFA-1 in the adherent cell population were significantly higher than those in the nonadherent cell population. Moreover, the CD4 to CD8 ratio of the HLA-DR+ cells in the EC-adherent T cells was significantly higher than that in the nonadherent cells. Collectively, these results indicate that increased adherence of T cells to EC in HAM patients is based on the increase of activated T cells with high density LFA-1 expression in the peripheral blood. Moreover, CD4+ HLA-DR+ cells exhibited more adhesive activity to EC than CD8+ HLA-DR+ cells, suggesting that activated CD4+ cells, rather than activated CD8+ cells, may be important as the first trigger for T cell-infiltration to the central nervous system in the immunopathogenesis of HAM.