Role of human leucocyte antigen (DQ) in acute renal allograft rejection: A single center study

Human leukocyte antigen (HLA) system is a very polymorphic gene complex encoding for cell surface proteins. Kidney transplantation (KT) is considered the optimal renal replacement therapy. Donor-specific antibodies (DSA) against HLA class II antigens are more common than class I. This study aimed to determine the role of HLA (DQ) in acute rejection of renal allograft. This study included 43 KT recipient donor pairs. HLA typing (A, B, DR) of donor and recipient and flowcytometry cross matching results pre transplantation were collected from patients' files. Panel Reactive Antibody (PRA) classes I and II were done to recipients pre transplantation. PRA classes I and II and HLA-DQ genotyping were done to recipients 15-16 weeks post-transplantation. Rejection occurred in 9.3% recipients. Recipients with positive PRA class II had a statistically significant higher percentage of rejection (25.0%) compared to (0.0%) of those with negative PRA class II (p=0.029). Recipients with positive anti HLA-DR antibodies (Abs) and anti HLA-DQ Abs had statistically significant higher percent of rejection (28.6%) compared to (0.0%) of those with negative anti HLA-DR Abs and anti HLA-DQ Abs (p= 0.016). Recipients with positive anti HLA-DQ4 Abs or anti HLA-DQ5 Abs had a statistically significant higher percent of rejection (50%) compared to (5.1%) of those without anti HLA-DQ4 Abs or anti HLA-DQ5 Abs (p=0.037). Recipients with positive anti HLA-DQ9 Abs had a statistically significant higher percent of rejection (30%) compared to (3.0%) of those without anti HLA-DQ9 Abs (p=0.034). Recipients who received kidney from HLA-DQ mismatched donors had higher incidence (57%) of anti HLA-DQ5 antibodies and anti HLA-DQ6 antibodies compared to those with HLA-DQ matched donors (0.0%) (p= 0.018). In conclusion, anti HLA-DQ antibody was one of the most prevalent post-transplant PRA detected. Regarding acute rejection, there was no risk association between its occurrence and HLA-DQ mismatching.