Mobilization of lymphoblasts from bone marrow to peripheral blood in childhood acute lymphoblastic leukaemia: Role of 9-O-acetylated sialoglycoproteins

Childhood acute lymphoblastic leukaemia is characterized by aberrant proliferation and accumulation of malignant lymphoblasts in bone marrow (BM), followed by their migration into circulation. An enhanced cell-surface expression of ALL-associated 9-O-acetylated sialoglycoproteins (Neu5,9Ac2-GPs) was demonstrated. Present investigation reports a positive correlation between the increased density of Neu5,9Ac2-GPs on lymphoblasts and their mobilization from BM involving enhanced Neu5,9Ac2 on CD45 demonstrating modulation of FAK and ERK molecules. In contrast, a small population of cells, identified as haematopoietic precursors, with comparatively lesser Neu5,9Ac2-GPs showed increased binding towards BM stroma. Thus, Neu5,9Ac2-GPs is a developmentally regulated oncofoetal antigen, whose up-regulation is imperative in the interaction between lymphoblasts and BM stroma, governing their mobilization into circulation.