The expression pattern of adhesion molecules and their role of the tumor cells in patients with multiple myeloma]

The expression pattern of beta 1 integrin on the surface of tumor cells in patients with multiple myeloma (MM) is reviewed and compared with that of other B cell malignancies. The expression pattern of beta 1 integrin of plasma cells of healthy individuals was also compared with that of malignancies of plasma cells. Normal immature CD10+ B cell precursors in bone marrow are alpha 4+ and alpha 5+, while mature peripheral B cells are alpha 4+ and alpha 5+. In contrast to mature peripheral B cells, it is reported that plasma cells are alpha 4+ and alpha 5+. There are three points following in the phenotype characteristic of MM cells; (i) MM cells are alpha 4 strong positive, (ii) MM cells are beta 1 strong positive and (iii) MM cells are alpha 6strong positive. Because alpha 6+ cell lines of malignant plasma cells showed spread and chemotaxis on stimulation with laminin, alpha 6 beta 1 integrin might contribute of MM cells to transit laminin rich basement membrane of blood vessel to exit to the extravascular space. The difference of the phenotype between plasma cells and MM cells is the expression of alpha 5; plasma cells express alpha 5, but MM cells are lost in one half of the cases. The functional role of VLA-5 in MM cells is reviewed.