Effect of Aflatoxin B I upon Phytohemagglutinin-Transformed Human Lymphocytes 1

The aflatoxins are a group of closely related toxic metabolites produced by certain strains of the mold Aspergillus flavus. Since the report that an outbreak of toxicity in poultry was due to contamination of peanut meal with aflatoxin 1 , there has been a growing literature concerning the toxic 2 , carcinogenic 3 , 4 and teratogenic 5 effects of aflatoxin and its most abundant and potent component, aflatoxin B₁ 6 .

Carcinogens have been observed to depress immune mechanisms 7 , 8 , especially the cellular immunity which is responsible for homograft rejection 9 . Stutman 10 has reported a correlation between the sensitivity of various strains of mice to tumor development with 3-methylocholanthrene and immune depression by the carcinogen. Since lymphocyte transformation is considered to be a manifestation of lymphocyte or cellular immunity 11 , it was decided to investigate the effects of aflatoxin B₁ on in vitro transformation of human peripheral blood lymphocytes by phytohemagglutinin and specific antigens.

Materials and Methods. Peripheral blood samples were obtained from patient volunteers at the Medical Center Hospital of Vermont who were not receiving corticosteroids or tranquilizers and who were not seriously ill. After the venipuncture, peripheral blood lymphocyte cultures were established by the method which has been described previously 12 . In brief, the bulk of the polymorphonuclear leukocytes and monocytes was removed by adherence to soft glass and the lymphocyte-enriched buffy coat washed repeatedly to remove autologous plasma. The final leukocyte concentration was 40% to 70% small lymphocytes, and 10⁶ lymphocytes/ml were suspended in 3 ml of medium (Minimal Essential Medium-Spinner) containing 20% fetal calf serum, 50 μg/ml of streptomycin, and 160 units/ml of penicillin.