EXPRESSION OF "CD54 AND CD621" BY LYMPHOID CELLS IN ACUTE LYMPHOBLASTIC LEUKEMIA IN CHILDREN

Abstract

Acute lymphoblastic leukemia is a biologically heterogeneous disorder that may develop as a consequence of malignant transformation I of a single abnormal progenitor cell at any point during the multiple

stages of normal lymphoid differentiation.

Normal hematopoiesis occurs within BM under influence of marrow microenvironment. These influences include cellular, cytokine and extracellular matrix interactions, all contribute to an environment that allows the hematopoietic progenitor cells to proliferate and differentiate normally.

Adhesive interaction between hematopoietic cells and a specialized microenvironm,ent within BM play a critical role in regulating normal haemopoiesis and egress of mature blood cells into circulation. Therefore it has been hypothesized that altered expression or function of adhesion molecules on leukemic blasts could contribute to the evolution and biological behavior of acute leukemias. Also determining the egress of blasts into peripheral blood and homing of others to extramedullary sites.

Thus, in acute leukemias, egress of blasts into peripheral blood might be due to alteration of adhesive capacities of leukemic cells. Three families of cell adhesion molecules (CAMs) which may mediate cell-cell or cell-matrix interactions have been identified. These families are: 1) The immunoglobulin superfamily, 2) The integrin family and the 3)