EXPRESSION OF HUMAN LEUKOCYTE ANTIGENS GENETIC POLYMORPHISMS IN PATIENTS WITH DIFFUSE LARGE B‐CELL LYMPHOMA

Abstract

Introduction: Diffuse Large B- cell Lymphoma (DLBCL) is characterized by genetic and clinical heterogeneity. Different loci within the human leukocyte antigen (HLA) region have been implicated in susceptibility and disease control of DLBCL. Methods: HLA typing was performed using Sequence-Specific Oligonucleotide (SSO) and Sequence-Specific Primer (SSP) in 60 DLBCL patients and 250 healthy adult donors from local Bone Marrow registry. Statistical analysis was conducted with version 29.0 of IBM SPSS. The phenotypic frequencies of HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 between patients and controls were compared with the 2-sided Fisher’s exact test. Results with p-value < 0.05 were considered statistically significant. Odds Ratios (OR) with 95% Confidence Intervals were calculated to further strength the results. Additionally, a follow-up analysis was performed by calculating Bonferroni-adjusted p-values (pc). Thereafter HLA polymorphisms that showed statistically significant difference were included in univariate and multivariate survival analysis together with the patients clinical-biological characteristics (age, stage, LDH, R-IPI). The R programming language, version 4.2.2 and specifically the “survivalAnalysis” package version 0.3.0. were used to investigate the associations of each factor with the Overall Survival (OS) and the Progression Free Survival (PFS). Results: DLBCL patients displayed a lower frequency of HLA-C*12 (6.7% vs. 34.7%, p = 0.001, pc = 0.00001, OR = 0.13, 95% CI [0.05, 0.38]), HLA-DRB1*16 (15% vs. 29.7%, p = 0.02, pc = 0.04, OR = 0.42, 95% CI [0.19, 0.89]) and HLA-DRB1*03 (58.3% vs. 77.5%, p = 0.02, pc = 0.01, OR = 0.40, 95% CI [0.22, 0.74]) compared to healthy individuals. In univariate analysis only advanced stage, high LDH and low versus high R-IPI had statistically significant impact on OS (p values 0.007, 0.003 and 0.002 respectively) and PFS (p-values 0.001, 0.002 and <0.001 respectively). Interestingly the Cox regression analysis used to evaluate the impact of LDH together with the HLA-DQB1*03 polymorphism on OS showed that although normal LDH is a good prognostic factor with HR = 0.33 95% CI [0.17 – 0.65] p-value = 0.001), the combination of normal LDH with DQB1*03 with HR 2.07 95% CI [1.06–4.07] indicates a significantly increased risk of death (p-value = 0.034). Regarding PFS the LDH- DQB1*03 model displayed also statistical significancy (p = 0.001) in a similar way with DQB1*03 increasing the risk of death while keeping LDH within normal ranges. Conclusions: Our results suggest that DLBCL patients express certain genetic types of HLA in lower frequency compared to healthy individuals. Antigens represented less frequently may act protectively in the development of the DLBCL. However, the presence of rarely represented HLA types failed to prove any positive impact on OS and PFS indicating the complexity of DLBCL pathogenesis. Keywords: aggressive B-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers No conflicts of interests pertinent to the abstract.