Determination of the PRA Positivity Percentage in Male Patients with Chronic Kidney Disease by Using Flow Cytometry Technique

Abstract

The antibodies directed against human leukocyte antigen (HLA) molecules, which play a crucial role in allograft histocompatibility, are called anti-HLA antibodies. Anti-HLA antibodies against foreign HLA molecules may be present in patients with chronic kidney disease even before transplantation. The panel reactive antibody (PRA) test is used to measure the renal transplant candidate’s immune sensitivity to HLA molecules other than their own HLA molecules by assessing the diversity of anti-HLA antibodies in the blood of these patients. This study aimed to determine the PRA values and the percentage of PRA positivity of Turkish male patients with chronic kidney disease (CKD), who had not been sensitized by the major known causes (those with no history of organ or tissue transplantation, those with no history of blood transfusion), who had not been diagnosed with any autoimmune diseases, and who had not been under immunosuppressive treatment. The study included 60 male patients aged over 18 years. All of the patients were followed up with a diagnosis of CKD at the Nephrology Clinic, Internal Medicine Department, Akdeniz University Medical Faculty Hospital. None of the patients included in the study was sensitized by a known mechanism previously (they did not have blood transfusion or organ transplantation). Glomerular filtration rate (GFR) levels of all patients were below the level of 60 mL/min/1.73 m2. Patient data including their age information, etiology of CKD, accompanying diseases, and information about dialysis modalities were recorded. HLA antibody percentage was determined by the flow cytometry technique. Statistical data analysis was performed by using SPSS 22.0 (Statistical Package for Social Sciences, Version 22.0). The values of p less than 0.05 were considered statistically significant. Twenty patients were receiving dialysis treatment due to end-stage renal disease. Of the 60 patients included in the study, 25% showed PRA positivity; 28.3% of all study patients were found to be positive for anti-HLA class I antibodies and 26.7% of all study patients were found to be positive for anti-HLA class II antibodies on separate analysis for anti-HLA class I and anti-HLA class II antibody positivity. When the patients were categorized as PRA negative and PRA positive in two groups, there were no differences between the groups according to mean age, percentage of hemodialysis patients, percentage of peritoneal dialysis patients and presence of accompanying chronic diseases (such as hypertension, type 2 diabetes mellitus, hyperlipidemia, nephrolithiasis, coronary artery disease). In addition to this, evaluation of the GFR levels showed that the PRA positive group contained a significantly higher percentage of end-stage renal disease patients (GFR <15 mL/min/1.73 m2) as compared with the PRA negative group. Detailed analysis of the percentages of PRA levels in the PRA positive patients, which was carried out to determine the degree of sensitization, showed that the PRA values were over 80% in 11.77% of the patients positive for anti-HLA class I antibodies. On the other hand, PRA values were within the range of 15%-80% in 88.23% of the patients who had anti-HLA class II antibodies. The PRA values were below 80% in all of the patients positive for anti-HLA class II antibodies and those positive for both anti-HLA class I and class II antibodies. In conclusion, PRA levels of the candidates for kidney transplantation should always be measured to assess their state of sensitization before transplantation, even though they have no risk factors known to cause anti-HLA antibody development.

Keywords

• Chronic kidney disease
• Flow cytometry
• Anti-HLA antibodies
• Renal transplantation