REQUIREMENT FOR CD44 IN PROLIFERATION AND HOMING OF HEMATOPOIETIC PRECURSOR CELLS

The hematopoietic form of the adhesion molecule CD44 is known to be in volved in lymphocyte maturation and homing. To define lineage and stag e of maturation, which requires expression of CD44, murine long-term b one marrow cultures were established. Stroma formation and proliferati on of early as well as committed erythroid, myeloid, and lymphoid prog enitors were evaluated under the influence of monoclonal anti-CD44 ant ibodies, Although the formation of stromal elements was not affected, formation of cobblestone areas was completely abolished. [H-3]thymidin e suicide confirmed that anti-CD44 treatment interfered with the proli feration of early and committed hematopoietic progenitor cells, In add ition, homing and seeding of bone marrow cells was impaired by anti-CD 44. The data are indicative of a dual functional mode of CD44, in adhe sion and proliferation of hematopoietic progenitors and confirm an ess ential requirement for the molecule in early stages of hematopoiesis.