Expression of complement regulatory proteins on erythrocytes from patientswith idiopathic focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a heterogeneous group of disor ders with respect to aetiology, morphology, clinical course and response to treatment. The present study assessed the expression of complement recepto r 1 (CR1), decay accelerating factor (DAF) and membrane inhibitor of reacti ve lysis (CD59) on the erythrocytes of FSGS patients using flow cytometry c ompared with their expression on the erythrocytes of minimal change nephrot ic syndrome (MCNS) patients. Significantly reduced expression of CR1, DAF a nd CD59 was observed on the erythrocytes of FSGS patients compared with the reduced expression of CR1 and enhanced expression of DAF on the erythrocyt es of MCNS patients. A significant inverse relationship was demonstrated be tween CR1 expression and proteinuria levels in FSGS patients (r = 0.55, P < 0.01). A follow-up study of 12 patients with FSGS after immunosuppressive therapy showed that the levels of complement regulatory proteins are signif icantly increased when the disease goes into remission. However, in patient s not responding to immunosuppressive therapy, levels of these proteins rem ained low. MCNS patients showed significant increases in CR1 and decreases in DAF expression during remission of the disease.