Involvement of CD44 variant isoform v10 in progenitor cell adhesion and maturation

CDU has been described repeatedly to be involved in hematopoiesis. Here, we addressed the question of functional activity of CD44 variant isoform v10 (CD44v10) in progenitor cell maturation by in vivo and in vitro blocking st udies with a monoclonal antibody and a receptor globulin. We became interes ted in this question by the observation that CD44v10 is expressed, although at a low level, on a subpopulation of bone marrow cells. Flow cytometry re vealed that 15%-20% of hematopoietic cells in the fetal liver and 25%-35% o f bone marrow cells in adult mice were CD44v10 positive. The majority of CD 44v10(+) cells was HSA(+)/J11d(+) and CD43(+). CD44v10 was not detected on CD4(+), CD8(+), IgM(+), or IgD(+) cells. A CD44v10 receptor globulin did no t bind to hematopoietic progenitor cells, but to stromal elements. The CD44 v10-CD44v10 Ligand interaction had a major impact on the adhesion of progen itor cells to stromal elements, When healthy animals received repeated inje ctions of either anti CD44v10 or the CD44v10 receptor globulin, committed p rogenitors were mobilized and significantly augmented numbers were recovere d in the spleen and the peripheral blood, Furthermore, the CD44v10-CD44v10 ligand interaction, which had no impact on progenitor expansion, influenced progenitor maturation, particularly of the B-cell lineage. Although the na ture of the CD44v10 Ligand remains to be explored. the supportive role of C D44v10 in progenitor maturation and, importantly, the efficient mobilizatio n of progenitor cells by anti-CD44v10 and a CD44v10 receptor globulin could he of clinical benefit in peripheral blood stem cell transplantation. (C) 1999 International Society for Experimental Hematology. Published by Elsevi er Science Inc.