cytotoxicity of aflatoxin B[1] in human lymphocytes

ABSTRACT

Aflatoxin B[1] [AFB[1]] is a naturally occurring carcinogenic and immunosuppressive compound. This study was designed to measure its toxic effects on human peripheral blood mononuclear cells [PBMC]. The study recruited 7 healthy volunteers. PBMC were isolated and cellular respiration was monitored using a phosphorescence oxygen analyser. The intracellular caspase activity was measured by the caspase-3 substrate N-acetyl-asp-glu-val-asp-7-amino-4-methylcoumarin. Phosphatidylserine exposure and membrane permeability to propidium iodide [PI] were measured by flow cytometry. Cellular oxygen consumption was inhibited by 2.5 micro M and 25 micro M of AFB[1]. Intracellular caspase activity was noted after two hours of incubation with 100 micro M of AFB[1]. The number of Annexin V-positive cells increased as a function of AFB[1] concentration and incubation time. At 50 micro M, a significant number of cells became necrotic after 24 hours [Annexin V-positive and PI-positive]. The results show AFB[1] is toxic to human lymphocytes and that its cytotoxicity is mediated by apoptosis and necrosis