Immunosuppressive effects of aflatoxin B1 on murine spleen cells culture

Abstract

The immunosuppressive effects, genotoxic effects, and consequent metabolisms of aflatoxin B1 (AFB1) were investigated under the culture of mouse splenocytes (SPLC) either alone or cocultured with at hepatocytes (HPTC). In attempt to elucidate the immunosuppressive effects with Balb/C mouse (Ah locus responsiveness), Polyclonal antibody response to LPS that used antibody forming cell (AFC) assay resulted in the suppression with dose-dependent fashion ($10^{-7}-10^{-4}$ M) at two system of cultures. And mitogen induced proliferative response to LPS and concanavaling A (ConA) that due to the proportion of incorporation of $^3$H-thymidine, were the similar pattern as above. Different strains, C57BL/6, C3H (Ah locus responsiveness), DBA/2 (Ah locus nonresponsiveness), showed the dose-related immunosuppression like Balb/C. Direct addition of AFB1 revealed the time-dependent suppression according to the period of pretreatment, and also the more suppression of antibody forming cells was obtained, which demonstrated an early requirement for AFB1 in culture in order to induce significant suppression. To assess the genotoxic effect against the DNA repairing and the single-strand breaks (SSBs), unscheduled DNA synthesis (UDS) assay and alkaline elution analysis were used respectively. In these studies with the cultured splencoytes, not only were significant levels of UDS measured in a time-dependent manner, but were DNA elution profile of SSBs induced detected with a same pattern. And, to examine the consequent metabolism under the culture of spleen cells alone, HPLC analysis was performed that showed the amount of aflatoxicol increased during the exposuring time designated. In summary, these studies indicated that a consequent metabolite following cultures of splenocytes were affected to the immunosuppressive and genotoxic effect. But what kinds of species of metabolite influenced was unknown.