METAPHASE YIELDS FROM STAPHYLOCOCCAL-ENTEROTOXIN-A STIMULATED PERIPHERAL-BLOOD LYMPHOCYTES OF UNIRRADIATED AND IRRADIATED AGED RHESUS-MONKEYS

The mitogen phytohemagglutinin (PHA) works well in both human and cyno molgus 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 thousa nds are required, e.g. in biological dosimetry studies. We show that s taphylococcal enterotoxin A (SEA), one of the most potent mitogens kno wn, at a concentration of 0.5 mu g/ml stimulated peripheral lymphocyte s 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 sa me animals. Whole blood was cultured for 96, 120 and 144 h for five ir radiated individuals and for two controls. All cells cultured with SEA produced a high MI with a peak response at 120 h whereas the same cul tures showed low MI for each PHA stimulated culture.