Evidence that interleukin 2 actively promotes both cell division and immunoglobulin secretion in human B cells

Three human Epstein-Barr virus transformed B cell lines were seeded at densities below their capacity for autostimulatory growth and exposed to recombinant human interleukin 2 (IL-2). IL-2 was found to stimulate DNA synthesis in all three lines, and the level of immunoglobulin secreted was also greatly increased. The experiments were repeated, but in this case the final cell numbers were established by the MTT method and the immunoglobulin secreted per 1,000 cells calculated. Both of these parameters were significantly elevated, indicating that the higher immunoglobulin levels recorded were due to the rate of secretion having been actively increased by IL-2 and were not merely artifactual, resulting from increased cell growth. Thus, IL-2 can actively promote DNA synthesis and cell division and can also increase immunoglobulin secretion in human B cells.