Immunosuppressive effects of aflatoxin in growing rats

The immunosuppressive potential of aflatoxin B₁ (AFB₁), the carcinogenic metabolite ofAspergillus flavus, was evaluated in growing rats. The weanling rats were subchronically exposed to 60, 300 and 600 µg AFB₁/kg body weight for four weeks on alternate days by oral feeding. Various parameters of cell mediated immunity (CMI) and humoral immunity were assessed in control and treated animals. CMI was evaluated by measuring delayed type of hypersensitivity (DTH) response and humoral by plaque forming cell (PFC) assay. The lymphoproliferative response assay for T- and B-cells was also performed. It was observed that AFB₁ selectively suppressed cell mediated immunity in growing rats. AFB₁ suppressed CMI at the 300 and 600 µg dose levels only as measured by DTH response assay. It is concluded that continuous low level exposure of aflatoxin to growing host may enhance its susceptibility to infection and tumorigenesis.Abbreviations AF Aflatoxin - AFB₁ Aflatoxin B₁ - CMI Cell mediated immunity - CPM Counts per minute - DTH Delayed type of hypersensitivity - GST Glutathione-S-transferase - LPS Lipopolysaccharide - PFC Plaque forming cell - PHA Phytohemagglutinin - SRBC Sheep red blood cells