Kell is not restricted to the erythropoietic lineage but is also expressedon myeloid progenitor cells

Anti-Kell antibodies have been shown to suppress fetal erythropoiesis, but little is known about their effect on myelopoiesis. We analysed the effect of Kell-related antibodies on granulocyte-macrophage colony-forming units ( CFU-GM) growth in semisolid medium using peripheral blood mononuclear cells (PBMNCs) from haematologically normal individuals. In addition to its inhi bitory effect on erythroid burst-forming units (BFU-E) growth, anti-Kell an tibodies significantly reduced CFU-GM colony formation from Kell-positive i ndividuals but not from Kell-negative donors. Moreover, anti-cellano and an ti-Kp(b) antibodies also inhibited the growth of CFU-GM from antigen-positi ve MNCs. These data indicate that Kell is not restricted to erythroid blood cells, but is also expressed on myeloid progenitor cells.