p26 : A Cell Surface Antigen Expressed Selectively by Hematopoietic Cells

A monoclonal antibody (MoAb) H5 (IgG2b) was obtained by fusion between SP2/0, mouse myeloma cell line and spleen cells from BC3Fl mice immunized with HEL, a erythroleukemia cell line. MoAb H5 precipitated a 26 kilodalton (KD) polypeptide in reduced condition. It reacted with platelets, monocytes, eosinophiles, 13% of lymphocytes, thymocytes and colony-forming units-granulocyte/monocyte (CFU-GM), but not with neutrophiles, red blood cells (RBC) and burst-forming units-erythroid (BFU-E). It also stained T-lymphoid leukemia cell lines but not B cell lines. Thus this antigen was expressed selectively by both myeloid and lymphoid lineages.