Effects of aflatoxin on the immune system: Evidence from human and mammalian animal research

Shortly after its discovery in 1960, aflatoxin – a group of fungal toxins or mycotoxins produced by the fungi Aspergillus flavus and A. parasiticus in food crops such as maize, peanuts and tree nuts – was found to cause liver cancer in humans and multiple animal species. Hence, regulations on maximum allowable aflatoxin levels in food worldwide have focused on protecting humans from aflatoxin's carcinogenic effects. However, aflatoxin may also have non-carcinogenic health effects (e.g., immunotoxicity) that are particularly relevant today. Our current review highlights the growing evidence that aflatoxin exposure adversely affects immunity. Here, we comprehensively evaluated human and mammalian animal studies that link aflatoxin exposure with adverse effects on the immune system. We organized the review by organism as well as by the effects on adaptive and innate immune functions. There is abundant evidence that aflatoxin exhibits immunotoxicity, and therefore may compromise the ability of both humans and animals to resist infections. However, the reported effects of aflatoxin on certain specific immune biomarkers are inconsistent in the existing literature. The extent of the immunotoxic effects of aflatoxin must be clarified, so that the contribution of such immunotoxicity to the overall burden of aflatoxin-related diseases can be established.