Decrease of CD4-positive T lymphocytes in workers exposed to benzidine and beta-naphthylamine.

T lymphocyte subpopulations (CD4+, CD8+, and CD3+ cells), Leu 11a-(CD16) positive lymphocytes, and total lymphocytes in peripheral blood in 52 male dyestuff workers were analyzed to determine the effects of benzidine and beta-naphthylamine on the human immune system. The workers had been exposed prior to 1972 to benzidine and beta-naphthylamine (aromatic amines) at a chemical plant. The dyestuff workers included 27 workers who had engaged in production of aromatic amines (i.e., high-exposure group) and 25 workers who had handled dyestuff at their job (low-exposure group). The total and relative numbers of CD4+ and CD3+ T lymphocytes in the high-exposure group were significantly lower than those found in the control (no-exposure) group (p < .01). Relative--but not total--number of CD16+ lymphocytes in the high-exposure group was significantly higher than in the control group (p < .05). However, there were no significant differences between the low-exposure group and control group with respect to all T lymphocyte subpopulations, CD16+, and total lymphocytes. Perhaps the number of circulating CD4+ T lymphocytes decreases in workers exposed to aromatic amines. It is concluded that measurement of CD4+ lymphocytes provides a useful biological marker of past exposure to aromatic amines.