THE EFFECT OF INTERLEUKIN-12 IN EX-VIVO EXPANSION OF HUMAN HEMATOPOIETIC PROGENITORS

We evaluated progenitor cell proliferation in cultures supplemented by different cytokine combinations in the presence or absence of IL-12. In cultures of low density cells, cytokine combinations including IL-1 2 were associated to a greater proliferation (up to 6.7 +/- 2.5 CFU-GM fold expansion), However, in cultures of purified CD34(+) cells the m ore efficient cytokine combination (147 +/- 49 CFU-GM fold expansion) was SCF, IL-3, IL-11 and MIP-1 alpha, and the addition of IL-12 did no t further enhance expansion of progenitors. These results indicate tha t accessory cells, lost in CD34(+) cell purification, could be in part responsible for IL-12 effect on progenitor cell proliferation. In CD3 4(+) cell cultures the addition of IL-12 led to CD19 mRNA generation, suggesting that IL-12 acts on haemopoietic cells with both myeloid and lymphoid potential.