Investigation of CD4+CD25+FoxP3+PD-1+ Regulatory T-cells and PD-1, PD-L1 mRNA Expression in the Bone Marrow in Newly Diagnosed Multiple Myeloma Patients

Aim: Multiple myeloma (MM) is a cancer that plasma cells.Increased regulatory T-cells (Tregs) have been associated with poor clinical outcomes in both newly diagnosed and treated MM patients.Treg cells are a T-cell subgroup that suppresses immune response.Programmed cell death protein 1 (PD-1) signaling pathway plays an essential role in Treg function and development.In literature, there is insufficient knowledge about the distribution of Treg cells in the bone marrow microenvironment despite the presence of these clinical studies in MM.In this study, we aimed to investigate PD-1 + Treg cell distribution and PD-1/PD-ligand 1 (PD-L1) gene expression levels in MM patients' bone marrow.Methods: Twenty newly diagnosed patients with MM and 9 idiopathic thrombocytopenic purpura patients were included in the study.Cluster of differentiation 4 (CD4), CD25, FoxP3 and PD-1 (CD279) expressions were evaluated by flow cytometry, and messenger ribonucleic acid (mRNA) expression of PD-1 and PD-L1 genes were determined using the quantitative polymerase chain reaction method.Results: In this study, no significant difference was found among CD4 + CD25 + FoxP3 + PD-1 + Treg cell levels, PD-1, and PD-L1 mRNA expression levels in the patient and control groups.There was no significant difference in Treg cell levels or in PD-1 and PD-L1 mRNA expression levels with respect to patient revised international staging system.There was no significant correlation between the expression of Treg cells, PD-1 mRNA, and PD-L1 mRNA levels (p>0.05).A strong correlation was found between PD-1 mRNA and PD-L1 mRNA levels (p0.0001,r=0.827).Conclusion: CD4 + CD25 + FoxP3 + PD-1 + Treg cell and PD-1, PD-L1 mRNA expression levels were found to be high in the patient group, although not significantly.We found a positive correlation between PD-1 and PD-L1 mRNA expression, supporting that PD-1/PD-L1 may be a prognostic biomarker.