Reduction of suppressor cell activities of human peripheral blood lymphocytes by a streptococcal preparation, OK-432.

The effect of a streptococcal preparation, OK-432 on suppressor cell activities of peripheral blood lymphocytes was investigated. Suppressor cell activities were significantly reduced when they were generated in vitro by concanavalin A (Con A) in the presence of OK-432. However, the reduction of suppressor cell activities was not observed when OK-432 was added in the effector phase. Similarly, a significant reduction of prostaglandin E2 (PGE2)-induced suppressor cell activities by OK-432 was observed. No increases of either T-cells with Fc receptors for IgG or OKT8 reactive T-cells were observed after Con A stimulation in the presence of OK-432. The suppressive effect of the soluble suppressor factors (SSF) was not abrogated by OK-432 and the release of SSF from cells activated by Con A was not found in the presence of OK-432. Thus, it is suggested that OK-432 might interfere with the induction of suppressor cells, but not with the expression of their activities.