Increased CD11/CD18 expression and altered metabolic activity on polymorphonuclear leukocytes from patients with polycythemia vera and essential thrombocythemia.

Functional studies of granulocytes in polycythemia vera (PV) and essential thrombocythemia (ET) are contradictory. In order to study the possible link between adhesion molecules and functional activity of polymorphonuclear leukocytes (PMNs) in these patients we measured the expression of CD11/CD18 glycoproteins and the oxidative burst of PMNs in patients with PV (13) and ET (18) and in 15 healthy voluntary donors. Experiments were performed by flow cytometry in total blood. The metabolism was stimulated by incubation with Escherichia coli and fMLP. Increased expression of CD11b/CD18 adhesion was obtained in PV and ET patients (p < 0.05 and p < 0.001). Studies of oxidative metabolism, stimulated by E. coli, showed a significantly reduced production of oxygen radicals in both groups of patients (p < 0.001). These data confirm the presence of a complex neutrophil dysfunction in PV and ET that probably reflects intrinsic abnormalities induced by changes in the cells' surface of the neoplastic clone and impaired signal transduction.