Aims: 

Polychlorinated biphenyls (PCBs) are persistent industrial chemicals that were widely used in the world. Toxic effects of different PCB congeners are structure-dependent. We have tested a non-coplanar congener, 2,2',5,5'-tetrachlorobiphenyl (PCB 52), and a coplanar congener, 3,3',4,4'-tetrachlorobiphenyl (PCB 77), for their effects on the T helper 1 (Th1) and T helper 2 (Th2) lymphocyte balance.

Methods: 

Venous blood samples were obtained from eight healthy male volunteers (age between 18 and 20). Lymphocytes were separated by density gradient centrifugation method. They were pooled and then cultured in 24-well plates at a seeding density of 3 × 10⁴/ml. The experiments were performed on 10 mg/ml concanavalin A (Con A)-stimulated and non-stimulated lymphocytes for determination of cytokine production profiles. Interferon-g (IFN-g, produced by Th1 cells) and interleukin (IL)-13 (produced by Th2 cells) concentrations were measured by ELISA in the supernatants at 24 and 48 hr after treatment with PCBs.

Results: 

The highest concentration of PCB 52 caused significant increases in IFN-g levels at 48 hr in both Con A-stimulated and non-stimulated media (p < 0.05). At 10 mM PCB 77 significantly raised IFN-g levels at 48 hr in Con A-stimulated medium (p < 0.05), but not non-stimulated medium. IL-13 levels were not significantly altered by PCBs (52 and 77) in both media (non- and Con A-stimulated).

Conclusion: 

Our results indicate that the cytokine production profile was significantly shifted to Th1 by coplanar and non-coplanar PCB congeners in human lymphocyte cultures, but effect of non-coplanar PCB congener was more potent than the coplanar PCB congener.

Acknowledgement: 

This study was supported by Firat University Research Foundation (FUBAP-1351).