Metaphase Yields from Staphylococcal Enterotoxin A Stimulated Peripheral Blood Lymphocytes of Unirradiated and Irradiated Aged Rhesus Monkeys

Abstract

The mitogen phytohemagglutinin (PHA) works well in both human and cynomolgus monkey (Macaca fascicularis) lymphocyte cultures to stimulate T cell proliferation. T cells from rhesus monkeys (Macaca mulatta) are less responsive than human cells, producing few metaphases when thousands are required, e.g. in biological dosimetry studies. We show that staphylococcal enterotoxin A (SEA), one of the most potent mitogens known, at a concentration of 0·5 µg/ml stimulated peripheral lymphocytes to grow with a mitotic index (MI) averaging 0·13 metaphases/cell in old, irradiated rhesus macaques. This was significantly greater (p < 0·001) than that produced by PHA (MI < 0·01) in lymphocytes from the same animals. Whole blood was cultured for 96, 120 and 144 h for five irradiated individuals and for two controls. All cells cultured with SEA produced a high MI with a peak response at 120 h whereas the same cultures showed low MI for each PHA stimulated culture.