[Characterization of a T-cell subpopulation with a new monoclonal antibody BL-TSub/2].

: The mab BL-TSub/2 binds to a majority (80%) of thymocytes. The antigen isolated from these cells has an apparent molecular weight of about 170 kDa. The mab BL-TSub/2 recognized antigen is expressed on approximately 50% of mature T cells in peripheral blood. The mab BL-TSub/2 does not bind to monocytes, granulocytes, platelets and CD16+NK cells. The antigen is possibly present on a part of peripheral B cells in very low density. Double labelling experiments showed that about 30% of CD4+ and 60% of CD8+ cells react with the mab BL-TSub/2. This BL-TSub/2+ subset is not identical with T-cell subpopulations till now defined. Within the CD4+ subset the majority of BL-TSub/2+ cells is included in the CD45RO+ subset while only a small proportion is CD45RA+. However, the CD8+ BL-TSub/2+ cells are mostly CD45RA+ with only few cells belonging to the CD45RO+ subset.