Differential surface expression of cell adhesion molecules during granulocyte maturation

Abstract: Individual steps of granulocyte maturation, such as lineage commitment, proliferation, maturation, and migration from the marrow to the peripheral blood, may be influenced by distinct interactions with the bone marrow stroma. To identify candidates of membrane com-ponents involved in maturational stage-specific interac-tions, we studied changes in the expression of cell adhesion molecules along the granulocyte maturational pathway. Three-color flow cytometric measurements were used to measure levels of cell adhesion molecules along this path-way. The a chains of VLA-4 (CD49d) and VLA-5, the inte-grin 31 chain (CD29), and CD31 (PECAM-1) were ex-pressed in high density on all early myeloid cells but down-modulated during postproliferative maturation. CD44 and L-selectin were expressed on CD34 myeloid progenitor cells and mature granulocytes but down-modulated during the intermediate stages of maturation. The granulocyte receptor for endothelial selectins, sLex, was specifically expressed by myeloid progenitor cells. sLex was down-modulated during the intermediate stages of granulocyte maturation but up-regulated again during terminal maturation. In contrast, CD67, a putative granulocyte adhesion molecule, was negative on progeni-tors, transiently up-regulated during the intermediate stages of maturation, and almost absent from the surface of mature granulocytes. These results show that each stage of granulocyte maturation is associated with the expres-sion of a unique combination of cell adhesion molecules. L-selectin, CD44, and j31 integrins were regulated as previously described for immature lymphopoietic cells and may therefore play general roles in the compartmen-talization and development of leukocytes. In contrast, sLex and CD67 were specifically expressed by myeloid cells and could be specifically important for compartmen-talization of distinct phases of granulocyte maturation