IL-11 directly stimulates murine and human erythroid burst formation in semisolid cultures

The effect of interleukin-11 (IL-11) on cultures of bone marrow cells was investigated. We found that IL-11 increased, in a dose-dependent manner, the number of bursts in the presence of Epo in murine or human cells cultures. This effect was also observed in cultures of murine cells established in serum-free conditions as well as in cultures of CD34+ enriched human cells in serum-containing (but not serum-free) cultures. A linear relationship between the number of bursts and the plated cell number was observed with murine bone marrow cells or non-adherent mononuclear cells (NA-MNC) human bone marrow cells. Moreover, the effect of IL-11 was not abrogated when either anti-stem cell factor-receptor (anti-SCF-R), anti-IL-3, or anti-granulocyte/macrophage colony-stimulating factor (GM-CSF), three cytokines known to greatly synergize with IL-11, was added to cultures. These results lead us to conclude that IL-11 directly stimulates the proliferation of murine and human burst-forming units-erythroid (BFU-E).