ABSTRACT Background:

The impact of HLA-DPB1 compatibility and its role as a transplantation antigen in haploidentical-related hematopoietic stem cell transplant (haplo-R-HSCT) have not been established, and a negative effect on survival has been suggested.

Objective:

The objective of the determine was to study the frequency and clinical effects of incompatibility at the HLA-DPB1 locus in the haplo-R-HSCT setting.

Methods:

Clinical records and electronic files of 91 patients with a hematological disease who underwent haplo-HSCT from January 2009 to October 2017 in a university medical center were scrutinized. Overall survival (OS) was estimated by the Kaplan-Meier method; the cumulative incidence of transplant-related mortality (TRM) and relapse rates was determined. Acute graft-versus-host disease was assessed by binary logistic regression. Cox regression model with a 95% confidence interval was used to examine the association between the different variables and their effect on OS.

Results:

Of the 91 donor-recipient pairs, 24 (26.37%) shared complete DPB1 identity, 60 (65.93%) had a mismatch at one allele, and 7 (7.70%) were mismatched at two alleles. Twenty-four different HLA-DPB1 alleles were found; the most frequent were DPB1*04:01 (34.1%) and DPB1*04:02 (27.5%). Two-year OS, the cumulative incidence of TRM and relapse was 51.3 ± 6.8%, 28 ± 6% and 60 ± 7.8% for all haplo-related transplants, respectively, with no statistical difference between HLA-DPB1 matched and partially matched patients. In Cox regression analysis, no risk factors associated with OS, TRM, or relapses were identified.

Conclusion:

HLA-DPB1 mismatching in the haplo-R-HSCT setting did not influence transplant outcomes and was clinically tolerable. A high degree of homozygosity was found.