DECREASE OF CD4-POSITIVE T-LYMPHOCYTES IN WORKERS EXPOSED TO BENZIDINE AND BETA-NAPHTHYLAMINE

T lymphocyte subpopulations (CD4+, CD8+, and CD3+ cells), Leu 11a-(CD1 6) positive lymphocytes, and total lymphocytes in peripheral blood in 52 male dyestuff workers were analyzed to determine the effects of ben zidine and beta-naphthylamine on the human immune system. The workers had been exposed prior to 1972 to benzidine and beta-naphthylamine (ar omatic amines) at a chemical plant. The dyestuff workers included 27 w orkers who had engaged in production of aromatic amines (i.e., high-ex posure group) and 25 workers who had handled dyestuff at their job (lo w-exposure group). The total and relative numbers of CD4+ and CD3+ T l ymphocytes in the high-exposure group were significantly lower than th ose found in the control (no-exposure) group (p < .01). Relative-but n ot total-number of CD16+ lymphocytes in the high-exposure group was si gnificantly higher than in the control group (p < .05). However, there were no significant differences between the low-exposure group and co ntrol group with respect to all T lymphocyte subpopulations, CD16+, an d total lymphocytes. Perhaps the number of circulating CD4+ T lymphocy tes decreases in workers exposed to aromatic amines. It is concluded t hat measurement of CD4+ lymphocytes provides a useful biological marke r of past exposure to aromatic amines.