Study of the ratio of Treg/Th1 and Treg/Th2 lymphocytes in Hodgkin's lymphoma patients and its relationship with disease prognosis

Background and purpose: CD4+CD25+FOXP3+ regulatory T cells (CD4+CD25+FOXP3+ Tregs) are a group of T lymphocytes that play an important role in regulating immune system responses by suppressing the activity of other T cells and establishing homeostasis in the immune system. Th1 and Th2 cells are other groups of CD4+ cells that play important functions in inducing inflammatory immune responses. Considering the important role of Treg, Th1 and Th2 cells in immune responses in patients with lymphoma, in this study the ratio of Treg/Th1 and Treg/Th2 lymphocytes in the peripheral blood of patients with Hodgkin's lymphoma who are in different phases of the disease (new cases, recovered and relapsed cases) and their relationship with the clinical parameters of the patients were evaluated. Methods: In this cross-sectional study, the frequency of Treg, Th1 and Th2 lymphocytes in the peripheral blood of 47 Hodgkin's lymphoma patients who were at different phases of the disease was measured with flow cytometry method and then the ratio of Treg/Th1 and Treg/Th2 populations was determined. Mann-Whitney U test was used to compare two groups and Kruskal-Wallis test was used to compare more than two groups. P-value <0.05 was considered as significant. Findings: The results showed that there was a significant decrease in the ratio of Treg/Th1 lymphocytes in recovered cases (% 0.025) and relapsed cases (% 0.007) compared to new cases (% 0.16) (with *P<0.001 and *P<0.001, respectively) and also in relapsed cases compared to the recovered ones (*P=0.023). Regarding the ratio of Treg/Th2 lymphocytes, a significant decrease was also observed in recovered cases (0.43%) and relapsed cases (0.34%) compared to the new cases (4.27%) (*P<0.001 and *P< 0.001, respectively). Also, considering the IPI risk parameter, the proportion of Treg/Th1 cells in lymphoma patients in the low-intermediate risk group was higher than in the high-risk group (median 0.031% vs. 0.013%; *P=0.007). In addition, the increase in the ratio of Treg/Th1 and Treg/Th2 cells in Hodgkin lymphoma patients was higher in the group with PS<2 than in the PS≥2 group (median 0.036% vs. 0.013%, *P=0.001 and 0.78% vs. 0.37%, *P=0.013; respectively). Conclusion: The results of this study showed that the ratio of Treg/Th1 and Treg/Th2 lymphocytes is related to better response to treatment and favorable prognosis in Hodgkin's lymphoma patients.