Immune effects of polychlorinated biphenyls, smoking and alcohol

Polychlorinated biphenyls (PCB) have been shown to exert some immune effects. Here we analysed their effects also on immune parameters not previously studied such as TCR α-β, TCR γ-δ and regulatory T cells (Treg), taking into account the specific and cumulative interference of smoking and alcohol. The study subjects consisted of 26 male workers in a steelworks factory, employed in the electrical maintenance sector, with previous exposure to a mixture of PCB (exposed subjects), and 30 male workers with no occupational exposure to PCB (controls). All subjects were given a questionnaire and peripheral venous blood samples were taken to determine serum PCB (33 congeners), total cholesterol and triglycerides, leukocytes, total lymphocytes and the T lymphocyte subpopulations (TCR α-β, TCRγ-δ, CD4+ and Treg lymphocytes). PCB, even though at a very low concentration, were significantly higher in exposed subjects than controls, and were significantly correlated with age. Monocytes% and CD4+ were significantly reduced in the exposed subjects as compared to the controls. The serum concentration of PCB positively correlated with TCR α-β, and negatively with TCRγ-δ. Treg lymphocytes showed a positive dependence on tobacco smoking, while the monocytes% and CD4+ showed a negative and positive dependence, respectively, on alcohol intake. Our results seem to show some effects of slight exposure to PCB in particular reducing the relative concentration of TCRγ-δ. This effect can favour indirectly the increase in Treg induced by smoking, the anti-inflammatory or proinflammatory/fibrogenetic/angiogenetic effect of which, exerted by produced cytokines, particularly TGF-β, deserves further clarification.