Only adult hemoglobin is produced in fetal nonerythroid x MEL cell hybrids.

In order to test whether the ontogenetic origin of human parental cells influences the expression of globin genes, we did fusions of mouse erythroleukemia (MEL) cells with fetal or adult nonerythroid cells and we assessed globin expression in hybrids. For selection of hybrid clones we used a monoclonal antibody that recognizes a human chromosome 11-linked cell surface marker. Globin expression was assessed with fluorescent antibody labeling, globin isoelectric focusing, and S1 nuclease mapping. Chromosome 11-containing hybrids from human nonerythroid cells (adult or fetal lymphoid cells; fetal fibroblasts) produced human adult (beta) but not fetal (gamma) globin chains. These results suggest that the MEL x nonerythroid cell hybrids express the adult human globin independent of whether the human cells derive from the fetal or from the adult stage of human development. Our findings, together with previous observations in MEL x fetal erythroid or MEL x HEL hybrids, show that the globin program of the parental human cell is the main determinant of the expression of fetal human globin in these hybrids.