BB1-3, A TRANSGENIC HYBRID CELL-LINE WITH ERYTHROID AND MEGAKARYOCYTIC DIFFERENTIATION POTENTIAL THAT EXPRESSES HIGH-LEVELS OF HUMAN GAMMA-GLOBIN AND HUMAN BETA-GLOBIN

We have characterized a murine hybrid cell line, Bb1-3, generated by t he fusion of mouse primary erythroblasts with MEL cells, It proliferat ed in serum-free medium and displayed a low level of spontaneous eryth roid and megakaryocyte differentiation. Terminal erythroid differentia tion could be induced with HMBA and DMSO and was enhanced by serum. Tr eatment with phorbol esters resulted in a high proportion of megakaryo cytes and the expression of megakaryocytic specific lineage markers. B b1-3 cells contain a human beta-globin transgene that was expressed at levels of 20-50% of the endogenous mouse globin genes. Initially, exp ression was largely limited to the beta-globin gene but after adaptati on to serum free growth, equal expression of both the human gamma- and human beta-globin genes was observed. This cell line provides further evidence that the differentiation potential of mouse erythroleukaemia cells is not restricted to the erythroid lineage and should be useful to study the mechanisms underlying both developmental globin gene reg ulation and the terminal differentiation of bipotential erythroid/mega karyocytic progenitor cells.