A comparative evaluation of immunotoxicity of DDT and its metabolites in rats

Effects of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethene (DDE), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 2,2-bis(p-chlorophenyl) acetic acid (DDA) were comparatively evaluated on humoral and cell mediated immune (CMI) responses in rats. Rats were given a diet containing 200 ppm of the various test compounds for 6 weeks and were subsequently immunized with ovalbumin. DDT, DDE and DDD, all induced differential degrees of humoral and cellular immune suppression. There were (a) increases in albumin/globulin ratios, (b) suppression of IgM and IgG levels, and (c) attenuations in ovalbumin induced antibody responses. In CMI studies, there were marked inhibitions of (a) leucocyte and macrophage migration factors, and (b) delayed type hypersensitivity (DTH) reaction. Whereas, these effects were most marked with DDE and DDD, DDA did not elicit such immunomodulatory effects. It is inferred that suppression of immune responses by immediate DDT metabolites, DDE (and DDD and not DDA) is an important determinant of the toxicity of DDT (DDE > DDD > DDT) and the influence of this environmental pollutant in health and disease.