FUNCTIONAL-ROLE OF PECAM-1 CD31 MOLECULE EXPRESSED ON HUMAN CORD-BLOOD PROGENITORS/

CD31/PECAM-1 (platelet endothelial cell adhesion molecule-1) is a 130 kDa integral membrane protein of the immunoglobulin gene superfamily w ith the distinctive feature of being expressed on several cell types a ssociated with the vascular compartment. In the present study we repor t a novel, unique CD31 mAb termed IP28A which reacts with all CD34 mol ecule expressing hematopoietic progenitor cells and a subset of T, B a nd NK lymphocytes from human cord blood. Interestingly, we show that t he number of CFU-GM and BFU-E was significantly augmented in cord bloo d progenitor cultures when purified IP28A mAb was added to rhSCF plus rhGM-CSF and rhEpo, respectively. Thus, these results are of relevance in the field of hematopoietic stem cell transplantation as they revea l an agonistic property of the IP28A/CD31 mAb on the differentiation o f cord blood progenitor cells.