Interleukin 2 and Tumor Necrosis Factor α are Complementary for Proliferation of the Hematopoietic Stem Cell Line LyD9

This is the authors' abstract. We don't add key points for this paper.

We have shown that tumor necrosis factor alpha (TNF alpha) and interleukin 2 (IL-2) are complementary for stimulation of growth of the hematopoietic stem cell line, LyD9. Neither TNF alpha nor IL-2 alone could stimulate the proliferation of LyD9 cells even after pre-incubation with these growth factors. The number of high-affinity IL-2 receptors on LyD9 cells did not increase after incubation with IL-2 and TNF alpha. These results suggest that the proliferative response of LyD9 by TNF alpha and IL-2 is not mediated by receptor inducing activities. We used the induction of the proto-oncogenes c-myc and c-pim to characterize the proliferative stimulation by IL-2 and TNF alpha. Northern blot analysis revealed that the simultaneous addition of IL-2 and TNF alpha was more efficient than IL-2 alone for c-myc mRNA induction. However, the addition of TNF alpha and IL-2 could not increase c-pim mRNA more than the level induced by IL-2 alone. The results indicate that the two growth factors complement each other by transducing different types of growth signal.