The relationship between PD-1 and CTLA-4 gene variations and expression levels in patients with diffuse large B cell lymphoma

Objective: Diffuse Large B Cell Lymphoma (DLBCL) is heterogeneous in terms of clinical, morphological and cytogenetic features. DLBCL is the most common type of non-Hodgkin lymphoma with an aggressive course. As one of the treatment strategies for lymphoma, immunotherapy targets immune checkpoint inhibitors. The recent scholarship popularized the investigation of correlation of PD-1, PD-L1, CTLA-4 and CD80 genes to many diseases. Thus, the aims of this dissertation are i) examining the polymorphisms of these four genes that evidently are significant in relation to various cancer types, ii) evaluating the correlation of observed genetic variants with mRNA expression and protein levels, iii) contributing the pathogenesis of DLBCL. Methods: In the present research, the DNA sequencing method from peripheral blood samples of 20 patients were used to determine polymorphisms of PD-1, PD-L1, CTLA-4 and CD80 genes, a control group of 20 from the same age and gender as the samples was also considered. Expression levels of target genes were determined using the Real Time Quantitative PCR method. Expression (%) levels of target cells were then evaluated by flow cytometry method. IBM SPSS Statistics for Windows Version 22 and R.3.3.2 software were used to evaluate the obtained data. Results: It is observed that PD-1, PD-L1 and CTLA-4 expression levels were higher in the patients compared to the control group. The PD-1 (rs2227981), PD-L1 (rs4143815) and CTLA-4 (rs231775) polymorphisms can be associated with these gene expression levels. According to the Flow Cytometry results, only CD4+PD-1+ and CD4+PD-L1+ cell expression levels (%) were significant compared to the control group. Conclusion: It is important to detect PD-1, PD-L1 and CTLA-4 gene polymorphisms and related PD-1, PD-L1 and CTLA-4 expressions in DLBCL. In the light of our findings, we believe that these genes may contribute to the understanding of DLBCL pathogenesis and prognosis.