The plaque-forming cell response of human blood lymphocytes. I. PFC response of lymphocytes to formalin-treated staphylocci.

The plaque-forming cell and proliferative responses of human peripheral blood lymphocytes induced by formalin-treated Staphylococcus aureus of the Cowan strain were studied in vitro. Human blood mononuclear cells were incubated for 6 days with staphylococci in culture medium RPMI 1640 supplemented with 10% human AB serum. The number of anti-sheep erythrocyte plaque-forming cells was determined by the Jerne technique. Lymphocyte proliferation was measured by [³H]thymidine incorporation. Individual lymphocyte donors could be classified as high or low responders to staphylococci. Lymphocyte proliferation appeared necessary for the generation of plaque-forming cells. The plaque-forming cell response was greatly influenced by the source of the human AB serum used in the culture medium. The addition of hydrocortisone to the culture medium augmented the plaque-forming cell response. Human B lymphocytes prepared by passage through a column containing Sepharose 4B conjugated to anti-human F(ab)₂ generated plaque-forming cells when incubated with staphylococci. However, the addition of T lymphocytes to these B-lymphocyte preparations augmented the plaque-forming cell response to staphylococci.