CROSS-LINKING CD7 ON MYELOBLASTS RESULTS IN GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR PRODUCTION

CD7(+)CD34(+) lymphohematopoietic progenitor cells in bone marrow are capable of differentiating into either lymphocytes or myeloid cells. T he mechanism whereby these bipotent progenitor cells are regulated is not yet clear. In this study, we investigated the role CD7 may play in the development of bipotent cells using two myeloid progenitor cell l ines, KG-1 and KG-1a, as models for such cells. Our data showed that c ross-linking CD7 on KG-1 and KG-1a cells induced transcription, transl ation, and secretion of granulocyte-macrophage colony-stimulating fact or (GM-CSF). Anti-CD7 antibody also augmented the colony formation by KG-1 cells. Protein synthesis in KG-1 cells also increased as a result of anti-CD7 stimulation, These phenomena could be blocked by anti-GM- CSF, and supported the notion that the secreted GM-CSF was the primary mediator of CD7 effects, Together, these findings suggest that the in teraction between CD7 and its putative ligand may play an important ro le in hematopoietic development. (C) 1996 by The American Society of H ematology.