Antigenic Expression and Proliferative Status of Multilineage Myeloid Progenitor Cells (CFU‐GEMM) in Normal Individuals and Patients with Chronic Granulocytic Leukaemia

Abstract

We assayed the number of multilineage myeloid progenitor cells (CFU‐GEMM) in the blood and marrow of patients with newly diagnosed chronic granulocytic leukaemia (CGL). The mean number of CFU‐GEMM in the blood was increased 600‐fold and CFU‐GEMM in the marrow was doubled in the CGL patients compared with normal. A complement‐fixing monoclonal antibody with HLA‐DR specificity inhibited the proliferation of CFU‐GEMM from CGL blood to a greater extent than that of comparable cells in normal marrow. Using a hydroxyurea ‘suicide’ method we found that the proportion of CFU‐GEMM in proliferative cycle was higher in CGL blood than in normal marrow. We conclude that (1) CFU‐GEMM numbers are greatly increased in the blood of patients with CGL, (2) CFU‐GEMM express HLA‐DR antigens on their surface, and (3) the apparently increased expression of the antigen on CFU‐GEMM from CGL blood in comparison with CFU‐GEMM from normal marrow may parallel the relatively higher proportion of CGL CFU‐GEMM in cell cycle.