Alteration in the Balance between Type 1 and Type 2 Immune Responses among Lead Exposed Population

Abstract

Immunotoxic effect of lead was reported in several studies. However, overt cytotoxicity of major immune cell types was not evident in such studies and it was suggested that lead might rather affect the balance between T-helper 1 (Th1) and T-helper 2 (Th) immune responses cytokines. Such hypothesis was investigated in the current study. Aims: To Study the effect of environmental exposure to lead on blood lead (B-Pb) level and to investigate the balance between interleukin-4 (IL-4, one of Th2 cytokines) and Gamma interferon (IFN-γ, one of Th1 cytokines) and its relation to lead exposure and B-Pb in the study subjects. Study Design: The study was designed to be cross-sectional case-control study. Methodology: The study was conducted on 80 subjects, 46 of them were environmentally exposed to lead (exposed group) as a result of living near a secondary lead smelter and the other 34 socioeconomically matched subjects (control group) were recruited from a rural area and were not exposed to lead, neither environmentally nor occupationally. All subjects were interviewed, clinically examined and tested for whole B-Pb level, serum interleukin-4 (IL-4) and Gamma interferon (IFN-γ) levels. Results: A statistically significant higher B-Pb (P = .006) and serum IL-4 levels (P < .001) were observed in exposed group (when compared to the control group). On the other hand, serum IFN-γ was of significantly lower levels (P < .001) in exposed group than control group. A statistically significant negative correlation was found between B-Pb level and serum IFN-γ (r = -0.284, P = .011) in all subjects. Conclusion: Our results suggest that environmental exposure to lead alters the balance between Th1 and Th2 cytokine with a bias towards the later.