EFFECTS OF IN-VITRO CORTICOSTERONE ON CHICKEN T-LYMPHOCYTE AND B-LYMPHOCYTE PROLIFERATION

1. The effects of corticosterone and the time of its addition to cultu res, on concanavalin A (Con-A) and pokeweed mitogen (PWM)-induced lymp hocyte proliferation were studied. 2. Peripheral blood lymphocytes (PB L) were isolated from Cornell K-strain Single Comb White Leghorn immat ure male chickens and cultured with various concentrations of Con-A or PWM. Corticosterone, in different concentrations, was added to the cu ltures either 2 h before or 2 h after the addition of the respective m itogen. 3. Addition of corticosterone 2 h before the mitogens caused a significant suppression of lymphocyte proliferation in response to bo th Con-A and PWM stimulation. Also addition of corticosterone 2 h afte r the mitogens caused significant suppression of proliferation in resp onse to both mitogens; however, the degree of suppression was not as g reat. 4. The results indicate that after early activation events are i nitiated by the mitogens, lymphocytes are less sensitive to the effect s of corticosterone. Because less suppression was seen in the cultures preincubated with PWM than those with Con-A, it is likely that there are different sensitivities to corticosterone in the cell populations that respond to these mitogens.