Antigenic characteristics of erythropoietin dependent and independent erythroid progenitors (BFU-E and CFU-E) in polycythaemia vera and idiopathic myelofibrosis defined by monoclonal antibodies.

The antigenic characteristics of erythropoietin (Ep) dependent and independent ("endogenous") erythroid progenitor cells (BFU-E and CFU-E) from patients with polycythaemia vera (PV) and idiopathic myelofibrosis (MF) were studied using 9 selected murine monoclonal antibodies (McAbs) in a complement dependent cytotoxicity assay followed by culture in methyl cellulose. McAbs L343 (HLA-DR antigen) S3-13 and S17-25 reacted with about 50% of BFU-E in MF and PV. In contrast HLA-DR antigens were not presented on CFU-E. McAbs R1.B19, WHGS29.1, PMN29 and PM81 recognized the antigens on less than 25% of BFU-E and CFU-E. The reactivity of Ep-dependent and Ep-independent BFU-E and CFU-E was similar with the majority of McAbs. However, McAbs S4-7 and VIM-2 reacted with a higher proportion of Ep-independent BFU-E than of Ep-dependent BFU-E. These results indicate that Ep independent, neoplastic BFU-E in PV and MF are more mature than their Ep dependent counterparts. The antigens expressed on erythroid progenitor cells from patients with PV and MF were earlier found on BFU-E and CFU-E from normal bone marrow and peripheral blood, usually on a higher proportion of cells, than in myeloproliferative disorders.