[Factors contributory to suppressive effect of human suppressor T cells in vitro (author's transl)]

Factors affecting induction and expression of human blood suppressor cells including the concentration of concanavalin A (Con A), the exposure time of lymphocytes to Con A, and the ratio of suppressor cells and responder cells, were studied in Con A induced lymphocyte transformation by both the tube method and the microplate method. The most optimal concentration of Con A for suppressor cell induction was found to be 40 micrograms/ml (tube method) or 40 micrograms/well (microplate method). However, a range from 10 micrograms to 40 micrograms/ml or 10 micrograms to 80 micrograms/well was almost equally effective. At least 16 hr of incubation with Con A was required for generation of suppressor cells, but 2 hr incubation with Con A followed by 22 hr without Con A was also effective. As far as the effect of the ratio of suppressor cells to responder cells on the expression of suppressive effect is concerned, 1:1 was enough but 2:1 was more effective. There was no marked difference in results obtained by both methods. However, the microplate method is simple, quick and economic and, therefore, is highly recommended in our country.