Blastogenic factors: production by T and B lymphocytes. Effect on T and B cells.

The aim of the present report is to identify the cells responsible for the in vitro production of blastogenic factor and to evaluate the effect of blastogenic factor on T and B lymphocytes. Human T lymphocytes were purified by a nylon wool column filtration method and B-cell-enriched populations were purified by sedimentation of E rosettes on Ficoll-Hypaque. The results were summarized as follows: Both T cells and B cells can produce blastogenic factor. However, blastogenic factor produced by T cells differed in some respects from blastogenic factor produced by B cells. (a) Blastogenic factor produced in unmixed B-cell cultures stimulated both B cells and T cells to proliferate, whereas blastogenic factor produced in unmixed T-cell cultures stimulated only B cells. (b) The production of T-cell blastogenic factor was accelerated when stimulated by allogeneic cells. In contrast, the blastogenic activity of supernatants from mixed cultures of B cells was not different from that of supernatants from unmixed cultures. The significance of these findings for mixed leucocyte reaction is discussed.