Hagiwara T, Nagasawa T, Nagahisa H, Takizawa M, Osada M, Abe T
Division of Hematology, University of Tsukuba, Japan.
Exp Hematol. 1996 May;24(6):690-5.
Megakaryocytes generate cytoplasmic processes (CP) that penetrate endothelial cells in the bone marrow sinus, and these processes may release platelets into the circulation at their terminal stage. Adhesion between the CP and endothelial cells may be important during the extension of CP. We examined the expression of adhesion molecules of the integrin family (CDw49b, CDw49d, CDw49e, CDw49f, CD18, CD11a CD11c, and CD11b), the immunoglobulin superfamily (CD54, CD56, CD58, and CD31), the selectin family (ELAM-1, LECAM-1, and CD62), and CD44, CD41b, and CD42b on platelets, megakaryocytes, and megakaryocytes with CP. No specific adhesion molecules were observed on the megakaryocytes with CP. Three staining patterns of adhesion molecules-homogeneous, speckled, and accumulated-were observed on the megakaryocytes with CP, but not on those without CP. Platelet integrins (i.e., CD41a, CDw49b, CDw49e and CDw49f) and GPIb (CD42b) were strongly and homogeneously stained on the CP. GMP-140 CD62) was weakly stained, in a speckled pattern. CD31 (PECAM-1) was also weakly stained but accumulated selectively on the tip of the CP. ANTI-CD31 suppressed CP formation of megakaryocytes. We speculate that the homodimerization of CD31 expressed on the tips of CP and endothelial cells is important for the extension of the processes and for the migration of megakaryocytes.
巨核细胞产生细胞质突起（CP），这些突起穿透骨髓窦中的内皮细胞，并且这些突起在其终末阶段可能将血小板释放到循环中。在CP延伸过程中，CP与内皮细胞之间的黏附可能很重要。我们检测了整合素家族（CDw49b、CDw49d、CDw49e、CDw49f、CD18、CD11a、CD11c和CD11b）、免疫球蛋白超家族（CD54、CD56、CD58和CD31）、选择素家族（ELAM-1、LECAM-1和CD62）以及CD44、CD41b和CD42b在血小板、巨核细胞以及带有CP的巨核细胞上的表达。在带有CP的巨核细胞上未观察到特异性黏附分子。在带有CP的巨核细胞上观察到黏附分子的三种染色模式——均匀、斑点状和聚集状，但在没有CP的巨核细胞上未观察到。血小板整合素（即CD41a、CDw49b、CDw49e和CDw49f）和糖蛋白Ib（CD42b）在CP上呈强而均匀的染色。GMP-140（CD62）呈弱染色，为斑点状模式。CD31（PECAM-1）也呈弱染色，但选择性地聚集在CP的尖端。抗CD31抑制巨核细胞的CP形成。我们推测，在CP尖端和内皮细胞上表达的CD31的同源二聚化对于突起的延伸和巨核细胞的迁移很重要。
