Functional platelet‐derived growth factor‐beta (PDGF‐β) receptor expressed on early B‐lineage precursor cells

SUMMARY Growth and maturation of B lymphocytes from stem cells require a series of complex processes that are dependent at least in part on growth factors. Uncontrolled expression of receptors from these early growth factors may contribute to a leukaemogenesis of such early B cell progenitors. We show here that early pre-pre-B cells, but not mature B cells, express the PDGF receptor-beta (PDGFR-β). These receptors contain a protein tyrosine kinase domain which is activated upon ligation with PDGF in pre-pre-B cells. Further, pre-pre-B leukaemia cells seem to express more PDGFR-β compared with their normal counterparts, suggesting a role for these receptors in growth promotion of leukaemia cells.