Monoclonal antibody specific for granulocytic-lineage cells and reactive with human pluripotent and committed haematopoietic progenitor cells.

A murine monoclonal antibody (82H5, IgM class) has been developed that detects an antigenic determinant expressed by greater than 90% of normal granulocytes and 60-80% of light-density normal bone-marrow cells, including human pluripotential progenitors (colony-forming-unit-granulocyte, erythroid, macrophage, megakaryocyte; CFU-GEMM) and committed progenitors: granulocyte-macrophage (CFU-GM), erythroid (BFU-E), and megakaryocytic (CFU-MK). This antibody did not react with erythrocytes, monocytes, platelets, lymphocytes from normal peripheral blood, lymphoblasts from patients with acute lymphoblastic leukaemia, or with lymphoid cells lines. The 82H5-defined antigenic determinant was expressed on greater than 90% of leukaemic cells of promyelocytic, myelomonocytic and monocytic morphology, and cell lines KG.1, ML.1, HL.60, K562 and U.937. Cortical thymocytes were unreactive with 82H5. Treatment of human bone-marrow cells with granulocytic-specific monoclonal antibody 82H5 plus complement significantly inhibited colony formation (48-74%; P less than 0.05) of CFU-GEMM, CFU-GM, BFU-E, CFU-MK, whereas treatment with control monoclonal anti-Ia antibody plus complement caused 79-89% inhibition. This antibody reacted strongly with 3-fuc-NAc lactosamine when tested with a panel of synthetic carbohydrate structures. We conclude that 82H5 may be a useful probe for phenotypic analysis of leukaemic cells and investigation of haematopoiesis.