Kell is not restricted to the erythropoietic lineage but is also expressed on 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 inhibitory effect on erythroid burst-forming units (BFU-E) growth, anti-Kell antibodies significantly reduced CFU-GM colony formation from Kell-positive individuals but not from Kell-negative donors. Moreover, anti-cellano and anti-Kpb antibodies also inhibited the growth of CFU-GM from antigen-positive MNCs. These data indicate that Kell is not restricted to erythroid blood cells, but is also expressed on myeloid progenitor cells.