Polimorfismo HLA e resposta imune humoral aos antígenos HLA em candidatos ao transplante renal da região norte/noroeste do estado do Paraná

Abstract

The HLA systems (Human Leukocyte Antigen) have a prominent role among the biological systems involved in the rejection process. In this study, we evaluated the HLA class I (HLAA,-B and-C) and class II (HLA-DRB1, -DQA1 and -DQB1) allele frequencies and humoral immune response to HLA antigens in chronic renal patients, renal transplant candidates, from Northern/Northwestern of Parana State. HLA typing was performed by the method of polymerase chain reaction-sequence specific primers (PCR-SSO) associated with Luminex technology, using genomic DNA extracted from peripheral blood leukocytes. The evaluation of the presence of anti-HLA antibodies against a panel of HLA antigens (Panel-Reactive Antibodies - PRA) was performed by complement dependent cytotoxicity (CDC), CDC with the addition of anti-human globulin (CDC-AHG), CDC with the addition of dithiothreitol (CDC-DTT) and solid-phase immunoassay associated with Luminex technology (SPI; LS1PRA kit, One Lambda, Inc.), using serum samples. Determination the specificities of anti-HLA antibodies were performed by kits LS1PRA and LS2PRA (SPI; One Lambda, Inc.). The performance of CDC, CDC-AHG, CDC-DTT and SPI methods for detection of anti-HLA antibodies class I was analyzed in 70 serum samples from chronic renal patients. Mean PRA detected by SPI (37.5 ± 34.2%) was higher than the values detected by the other methods. Comparative analyses revealed significant difference between CDC and CDC-AHG (P <0.001), and between CDC and SPI (P <0.001), but not between CDC-AHG and SPI (P = 0.803). The performance of the CDC-AHG method for detection of anti-HLA antibodies was comparable to the SPI in the evaluation of percent class I PRA. The influence of HLA class I (HLA-A, -B, -C) and class II (HLA-DRB1, -DQA1, -DQB1) allele groups on humoral immune response to HLA antigens were studied in 319 chronic renal patients (198 males and 121 females). Of the total patients, 63.6% had positive PRA. PRA-positivity was significantly associated with female gender (P <0.001), transfusions (P <0.001) and pregnancies (P <0.001). The frequencies of HLA-B*14 (OR: 3.32; CI: 1.13-9.76), HLA-C*08 (OR: 3.98; CI: 1.38-12.38) and HLA-DRB1*16 (OR: 3.32; CI: 1.13-9.76) were significantly higher in patients with negative PRA compared with patients with positive PRA, suggesting that HLA class I (HLA-B*14, -C*08) and class II (HLA-DRB1*16) allele groups might be involved inthe decrease of humoral immune response to HLA antigens. The sensitization to HLA antigens and history of blood transfusion was evaluated in 236 chronic renal male patients awaiting their first kidney transplant. Of the total patients, 121 (51.3%) had positive PRA and 138 (58.5%) had previous history of blood transfusion. Transfusion history showed a significant difference between the PRA-positive and PRA-negative group (P <0.001). Sensitization to HLA antigens from transfusion occurred in 88 (37.3%) patients. Transfused patients had longer waiting times on dialysis when compared with nontransfused patients (P<0.01). Positivity of PRA class I or/and class II and median number of HLA class I or/and class II specific antibody HLA-specific were higher for those who received transfusion compared to those who did not received transfusion (P <0.05). Many patients continue to receive blood transfusions before transplantation, increasing the possibility of becoming sensitized. This study allowed the knowledge of HLA polymorphism and humoral immune response to HLA antigens in renal transplant candidates from North/Northwestern of Parana State.