[Production of activity stimulating an increase of clonal granulocytic precursors by normal B lymphocytes under the influence of various mitogens].

The effect of mitogen-stimulated (concanavalin A, Con A; phytohemagglutinin, PHA; pokeweed mitogen, PWM; Staphylococcus aureus Cowan I, SAC I) normal B lymphocytes on the clonal proliferation of granulocytic progenitors from marrow of healthy subjects (CFU-dG) was studied in diffusion chamber culture. PWM-, SAC- and Con A-stimulated B lymphocytes produced an humoral activity that increased the CFU-dG-derived colony formation. The highest growth-stimulating effect was induced by SAC I-preincubated B lymphocytes and to a lesser degree by PWM- or Con A-stimulated B cells. In contrast, PHA-preincubated and unstimulated B lymphocytes revealed no effect on the CFU-dG proliferation.