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 with the distinctive feature of being expressed on several cell types associated with the vascular compartment. In the present study we report a novel, unique CD31 mAb termed IP28A which reacts with all CD34 molecule expressing hematopoietic progenitor cells and a subset of T, B and NK lymphocytes from human cord blood. Interestingly, we show that the number of CFU-GM and BFU-E was significantly augmented in cord blood 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 reveal an agonistic property of the IP28A/CD31 mAb on the differentiation of cord blood progenitor cells.