EXPRESSION OF VLA MOLECULES ON ACUTE-LEUKEMIA CELLS - RELATIONSHIP WITH DISEASE CHARACTERISTICS

VLA molecules are involved in the adhesion of hematopoietic cells to t he bone marrow stroma and play a role in the mediation of cellular int eractions and migrations that are potentially important in the biology of acute leukemia (AL). We studied the expression of VLA-2 (CD49b), V LA-4 (CD49d), and VLA-5 (CD49e) by indirect immunofluorescence on leuk emic cells from 67 patients with acute myelogenous leukemia (AML) and 40 patients with acute lymphoblastic leukemia (ALL). VLA-2, VLA-4, and VLA-5 were expressed, respectively, on 13 +/- 17%, 33 +/- 29%, and 36 +/- 30% of AML cells with 20, 54, and 61% positive cases and on 22 +/ - 27%, 40 +/- 30%, and 39 +/- 29% of ALL cells with 29, 60, and 61% po sitive cases. Significant difference was neither noted between French- American-British (FAB) subtypes in AML or ALL nor between immunologic subtypes in ALL. There were highly significant correlations between th e expression of the three pl-integrins tested in both AML and ALL. In AML, expression of both VLA-4 and VLA-5 was associated with that of CD 14 (p=0.003 and p=0.01, respectively) and CD19 (p=0.006 and p=0.009, r espectively). Expression of VLA-5 was correlated with that of CD15 (p= 0.004). Expression of VLA-4 was associated with both a high initial bl ast cell count (p=0.01) and high percentage of bone marrow blast cell involvement (p=0.003). In ALL, expression of VLA molecules was correla ted neither with differentiation antigen nor with hematologic features . In AML, as in ALL, no significant correlation was noted between expr ession of VLA molecules and evolution of the disease.