Increase in CD57 + CD16 - lymphocytes in workers exposed to benzidine and beta-naphthylamine: assessment of natural killer cell subpopulations

Previously, we found a decrease in CD4+CD45RA+T lymphocytes in workers exposed to the aromatic amines (AAs) benzidine (BZ) and beta naphthylamine (BNA)]. For further investigation of the effects of AAs on lymphocyte subpopulations, we measured natural killer (NK) cell subpopulations using two-color staining with anti-Leu7 (CD57) and anti-Leu11 (CD16) monoclonal antibodies in peripheral blood in 78 male dyestuff workers. The workers had been exposed to AAs before 1972 at a chemical plant, either in the production of AAs (40 workers, high-exposure group) or in other work that involved handling dye-stuffs (38 workers, low-exposure group). The controls were 30 “healthy” male volunteers without a history of occupational exposure to AAs or hazardous chemicals. The number of CD57+CD16-cells in the high-exposure group was significantly higher than that in the controls (P<0.01, analysis of covariance with age as a covariate). No significant differences were found in CD57+CD16-, CD57+CD16+ and CD57-CD16+NK cells between the low-exposure group and the controls. It is suggested that a decrease in the number of CD4+ T lymphocytes following exposure to AAs might be compensated by the increase in CD57+CD16- cells, i.e. circulating peripheral lymphocytes with poor NK cell activity.