Treatment with recombinant human erythropoietin (rHuEpo) in a patient with paroxysmal nocturnal haemoglobinuria: evaluation of membrane proteins CD55 and CD59 with cytofluorometric assay.

We describe a 28-year-old man with paroxysmal nocturnal haemoglobinuria (PNH) and a high transfusion requirement. Prior to and during therapy with recombinant human erythropoietin (rHuEpo), we evaluated the levels of 'decay-accelerating-factor', CD55, and 'membrane-inhibitor-of-reactive-lysis', CD59, as markers of the disease, whilst CD58, a marker present on leucocytes, was utilized to monitor normal haemopoietic activity. The patient became transfusion independent 1 month after beginning rHuEpo and remains well. The analysis of CD55, CD59 and CD58 suggests that the efficacy of rHuEpo was due to a selective rHuEpo action on normal erythroid clones.