The assessment of native erythropoietin and antibodies to recombinant erythropoietin in haemodialysis patients

Abstract

Anaemia being one of the most severe complications of end stage renal disease is presently being managed with treatment by recombinant erythropoietin (RHuEPO). Recombinant erythropoietin (RHuEPO) produced by recombinant human DNA technology (RHuEPO) is becoming a standard part of therapy in chronic renal failure. In such patients anaemia is a leading cause of morbidity and mortality. Haemodialysis patients have grown dependent on RHuEPO therapy due their anaemia. The assessment of native erythropoietin levels and the detection of antibody levels in blood in the study were carried out to assist in the clear target of the treatment of anaemia. Haemoglobin levels were monitored over a trial period of six months during the RHuEPO therapy. Ferritin, transferrin saturation (T Sats %) and transferrin levels were monitored accordingly. Monitoring of erythropoietin levels in haemodialysis patients has been one of the first done in our population group in South Africa.Forty haemodialysis patients on RHuEPO therapy and ten haemodialysis patients not on RHuEPO therapy and ten healthy individuals from the Haemodialysis unit at Addington Hospital, Durban, South Africa were recruited to participate in the trial. Blood samples were collected then were centrifuged at 5 degrees celsius. Plasma was isolated, stored and subsequently used in enzyme linked immunosorbent assay (ELISA). Two ELISA were set up, one to measure EPO level and another for anti EPO antibodies. The dilutions of 1:50 were selected to detect the presence of antibodies. These have all been done in duplicates. Optical density of each sample was measured using a microplate reader at 450nm. The haemodialysis patients receiving RHuEPO presented with higher EPO levels as compared to the haemodialysis patients not receiving RHuEPO and the healthy individuals. However, in the study the HB levels were not increased over the trial period with higher RHuEPO doses. Higher doses of RHuEPO therapy showed no clear increase in haemoglobin levels. From a total of forty patients, twelve patients (35%) in the months of August and eight (25%) in the month of November were tested positive for antibodies to RHuEPO. Using statistical analysis, no correlation was observed between the antibody levels and the erythropoietin levels. However, we did not test whether the antibodies found were neutralizing or not. Bioassays for EPO may be used for that purpose.