Objective: To investigate the expression levels of the receptor for urokinase-type plasminogen activator (uPAR) on granulocytes and the soluble uPAR (suPAR) level in plasma from patients with paroxysmal nocturnal hemoglobinuria (PNH) and its clinical application in the diagnosis of this disorder.
Methods: Expression of uPAR, CD55 and CD59 was measured on granulocytes by using flow cytometry (FCM) and the level of suPAR in plasma by using immunoradiometric assay (IRMA) in 20 patients with PNH, 59 anemic patients with diagnoses other than PNH (18 with autoimmune hemolytic anemia, 6 with other hemolytic anemias, 26 with aplastic anemia and 9 with iron deficiency anemia) and 21 healthy individuals.
Results: In PNH patients, both the mean fluorescence intensity and percentage of positive fluorescence-activated granulocytes of uPAR, CD55 and CD59 were remarkably decreased, while in anemic patients with diagnoses other than PNH the results were not different when compared with those of the healthy individuals. The expression level of uPAR was reduced to the same extent as that of CD55 and CD59 on the PNH-affected granulocytes. In addition, some peak shape abnormalities (double peaks and/or peak tailing) in the histogram of fluorescence intensity were also found in PNH patients. The suPAR concentration of PNH plasma was (4.04 +/- 2.47) micrograms/L, being higher than that of the healthy individuals (1.73 +/- 0.96) micrograms/L (P < 0.01). And the percentage of positive fluorescence-activated granulocytes was inversely associated with the plasma suPAR level in PNH patients (r = -0.79, P < 0.01).
Conclusion: It is suggested that measurement of expression level of uPAR on granulocytes with FCM and suPAR in plasma with IRMA would be alteanative specific techniques for the diagnosis of PNH.