Background: Kidney transplantation remains the treatment of choice among end-stage renal disease patients and little emphasis has been given to the HLA DQ mismatch determination. The significance in renal outcomes has not been clearly defined. The objective of the study is to determine the association of HLA-DQ mismatches on biopsy proven acute rejection (BPAR), graft function and mortality at 1- and 3- years among living and deceased patients who underwent kidney transplantation.

Methods: This is a retrospective cohort of kidney transplantation performed from 2012 to 2017 in a tertiary renal referral center. Patients were divided into 0-, 1-, 2- HLA DQ mismatches. Continuous and categorical data were analyzed using Mann Whitney-U or Kruskal-Wallis and Chi-square or Fisher’s exact tests respectively. Kaplan-Meier Analysis, Log-rank test, Cox-regression and Multiple Linear Regression were used to determine the effect of HLA DQ on acute rejection, graft function and mortality up to 8 years post-transplant.

Results: Among 253 patients included in the study, majority were <50 years old males with non-diabetic nephropathy primarily chronic glomerulopathy and hypertensive nephrosclerosis. 106 patients (42%) have high immunologic profile and majority of patients had living donor. Among the population, 32%, 51% and 17% had 0-, 1-, 2- HLA DQ mismatches respectively. The BPAR among zero HLA-DQ mismatch was 1.25%, 5.12% and 12.23% at 1-, 3- and 5-year post transplant respectively. The BPAR among one HLA-DQ mismatch was 0.78%, 11.14% and 13.73% at 1-, 3- and 5-year post transplant respectively compared to those with two HLA-DQ mismatch with 2.33%, 9.30% and 17.52% at 1-, 3- and 5-year post transplant respectively. The eGFR of patients with zero HLA DQ mismatch had a median of 76 ml/min, 78 ml/min and 74.5 ml/min at 1-, 3- and 5-year post transplant respectively. Patients with one HLA DQ mismatch had median eGFR of 71 ml/min, 74 ml/min and 73 ml/min at 1-, 3- and 5-year post transplant respectively, while patients with two HLA DQ mismatches had 71 ml/min, 74 ml/min and 73 ml/min at 1-, 3- and 5-year post transplant respectively. The mortality with zero HLA-DQ mismatch showed 0%, 1.25 % and 5.57% at 1-, 3- and 5-year post transplant respectively. The mortality with one HLA-DQ mismatch showed 0%, 0.84% and 2.24% at 1-, 3- and 5-year post transplant respectively while mortality with two HLA-DQ mismatch showed 4.44%, 6.72% and 6.72% respectively. There was no significant difference in BPAR, graft function and mortality by HLA-DQ mismatch when stratified according to immunologic risk. Regression analysis showed no significant association between HLA DQ mismatches and 1- and 3- year BPAR, graft function and mortality.

Conclusion: The study showed that HLA-DQ mismatch was not a significant risk factor for acute rejection, graft function and mortality up to 8 years among kidney transplant recipients.