Quantitative expression of the adhesion receptors VLA-4, VLA-5, L-selectin, MAC-1, and ICAM-1 on the surface of CD34+ cells]

The aim of this work was to quantify by flow cytometry the main adhesion receptors on CD34+ cells. These cells were isolated from bone marrow (BM) or mobilized peripheral blood (PB). The proportions of CD34+/CD49d+ and CD34+/CD49e+ are weaker on PB cells, without quantitative expression variation. This phenotypic variation may induce CD34+ cells exist from BM into circulation, promoting the mobilization. The homing to the BM implicate the CD62L receptor, which expression was found more frequently and stronger on PB cells than on BM. The CD11b, CD18 and CD54 receptors are implicated in CD34+ cells adhesion to BM micro-environment. No significant variation in CD34+/CD11b+ and CD34+/CD18+ cells frequency was noted. Moreover, CD54 receptor was more frequently expressed on PB cells. Quantitative analysis revealed that CD18 was more strongly expressed on BM than on PB cells. This quantitative variation could promote progenitor adhesion by interacting with stromal cells. Finally, quantitative expression of the main receptors on CD34+ cells provides an original option for studying CD34+ cells during the mobilization, the homing or the adhesion to BM micro-environment.