Evidence for the Release of Mitogenic Factors by Both T and B Lymphocytes in the Human

Lymphocytes incubated with antigens or nonspecific stimulatory agents may release factors that induce DNA synthesis in other lymphocytes. The aim of this investigation was to determine whether such mitogenic factors (MF) are produced by both T and B cells in the human. Both T- or B-cell-enriched cell preparations from peripheral blood were found to release MF during or after incubation with phytohemagglutinin or pokeweed mitogen. Concanavalin A covalently bound to Sepharose triggered B-cell preparations to higher MF release than either T cells or unfractionated lymphocyte suspensions. These results strongly indicate that both T and B cells in the human are able to produce MF.