A monoclonal antibody (anti-Tac) reactive with activated and functionally mature human T cells. I. Production of anti-Tac monoclonal antibody and distribution of Tac (+) cells.

Abstract

A monoclonal antibody termed anti-Tac monoclonal antibody, which is reactive with activated and functionally mature human T cells, was produced by a somatic cell fusion technique. The reactivity of anti-Tac monoclonal antibody against various kinds of cells was determined by a complement-dependent cytotoxicity test. Anti-Tac antibody was reactive with a proportion of normal human peripheral blood T cells activated by PHA (54.7 ± 6.5%, mean ± SEM), Con A (20.6 ± 4.8), PWM (29.2 ± 2.6), SLO (25.3 ± 6.0), and allogeneic ceils (41.0 ± 5.8) but not with freshly separated resting T cells, B cells, monocytes, or B cells activated by EBV or PWM. Among various leukemic cells and cell line cells, 5 human cultured T cells (CTC) cultured with T cell growth-promoting factor(s) were reactive with anti-Tac antibody, whereas 4 long-term T cell lines (MOLT-4, CCRF-CEM, RPMI 8402, HSB-2) that do not require T cell growth-promoting factor(s) for growth, 2 long-term B cell lines (PA-3, RPMI 8392), 5 EBV-transformed B cell lines, leukemic T cells from patients with acute lymphoblastic leukemia (3 cases) and from those with Sezary syndrome (5 cases), and leukemic B cells from patients with chronic lymphocytic leukemia (4 cases) were not killed by anti-Tac antibody and complement. T cells reactive with anti-Tac antibody appeared before the marked increase in 3H-thymidine uptake in cultured T cells stimulated by Con A. Irradiation with 2000 R or mitomycin C treatment of cells did not prevent the appearance of Tac (+) cells in Con A- or PWM-stimulated T cell cultures, whereas culture with cycloheximide prevented the appearance of Tac (+) cells. These results indicate that the expression of Tac antigen requires protein synthesis but not DNA synthesis and cell division. The relationship between this anti-Tac antibody and other monoclonal antibodies directed to human T cells is discussed.