Separate but complementary roles for the two forms of interleukin 1 in the growth of transformed human B lymphoblasts.

Epstein-Barr virus (EBV)-transformed human B cells were seeded at densities below their capacity for autostimulatory growth and the effects of interleukin 1-alpha (IL-1-alpha), interleukin 1-beta (IL-1-beta) and B-cell growth factor (BCGF) were studied. When added separately, IL-1-alpha was able to support the growth of EBV-transformed B cells, as was BCGF. In contrast, IL-1-beta was unable to support the growth of these cells but was able to synergize with IL-1-alpha to promote cell growth. Further, the actions of BCGF and IL-1-alpha were seen to be synergistic, while those of BCGF and IL-1-beta were not. The secretion of immunoglobulin was not affected by these reagents. These findings suggest separate, but complementary roles for the two forms of human IL-1 in B-cell growth.