Characterization of physically different human T-cell subsets with monoclonal antibodies and biochemical markers

Abstract

Human T cells from thymus and blood, separated into subpopulations on continuous density gradients, were investigated for binding of monoclonal antibodies and activity of several enzymes. According to those parameters, several differences related to the specific gravity of the cells were found. Virtually all heavy thymocytes were positive for the monoclonal antibodies OKT 10, 8, 6, and 4, but did not bind to OKT 3. In contrast, a substantial part of the light thymocytes bound OKT 3 and OKT 4, but did not bind OKT 6 and OKT 8. In blood, heavy T lymphocytes were enriched in cells positive for OKT 8, whereas light lymphocytes contained more OKT 4-positive cells. Heavy peripheral T cells and thymocytes, which had an immature isoenzyme pattern of lactate dehydrogenase (LDH), and a poor proliferative response in vitro, had low activities of 5′-nucleotidase (5′NT) and of purine nucleoside phosphorylase (PNP) and a high activity of adenosine deaminase. Light peripheral T cells had a more mature LDH isoenzyme pattern and higher activities of 5′NT and PNP. We conclude that the poor proliferative response in vitro of heavy peripheral T cells must be due to multiple intrinsic properties, including a low stage of maturation and the occurrence of (precursors for) suppressor cells.