RÉSUMÉ
Objective:To investigate the changes of T lymphocyte subsets in peripheral blood of patients with diffuse large B-cell lymphoma (DLBCL) and its clinical significance.Methods:The clinical data of 99 DLBCL patients admitted to the First Affiliated Hospital of Xiamen University from January 2022 to January 2023 were retrospectively analyzed. T lymphocyte subsets in peripheral blood before and after treatment were detected by using flow cytometry. According to the disease status at the time of blood collection and detection, the patients were divided into the newly-diagnosed DLBCL group (28 cases), and the newly-treated remission DLBCL group (71 cases); and 40 healthy volunteers undergoing the physical examination during the same period were selected as the healthy control group. The proportion and absolute count differences of T lymphocytes and the related subsets in 3 groups were compared. Besides, the correlation among T lymphocyte subsets, the correlation of each subset with international prognostic index (IPI) score and treatment response in newly-diagnosed DLBCL patients were further analyzed.Results:The proportion of CD3 + T cells in newly-diagnosed DLBCL group was decreased compared with that in the healthy control group [(58±14)% vs. (67±7)%, P < 0.05]. The absolute count of CD3 + T cells in both newly-diagnosed group and the newly-treated remission group was reduced compared with that in the healthy control group [(875±483) /μl and (808±553) /μl vs. (1 374±279) /μl, P < 0.001]. The absolute count of CD4 + and CD8 + T cells in newly-diagnosed group was decreased compared with that in the healthy control group [(478±313) /μl vs. (695±154) /μl, (316±181) /μl vs. (525±193) /μl, all P < 0.001]. Both the proportion and absolute count of CD4 + T cells in the newly-treated remission DLBCL group were decreased compared with those in the newly-diagnosed DLBCL group and the healthy control group [(40±14)% vs. (53±14)% and (51±9)%, (313±247) /μl vs. (478±313) /μl and (695±154) /μl, all P < 0.05]. The porportion of CD8 + T cells was increased compared with that in the other two groups [(51±15)% vs. (37±12)% and (38±9)%, all P < 0.001]. Compared with the healthy control group, the effect/memory subsets proportion of regulatory T cell (Treg) and conventional T cell (Tcon) were increased in both newly-diagnosed DLBCL group and the newly-treated remission DLBCL group [(79±16)% and (84±12)% vs. (71±11)%,(72±16)% and (76±14)% vs. (62±13)%, all P < 0.05], and the proportion of CD127 + memory Tcon and CD8 + T cell subsets was reduced [(73±14)% and (66±20)% vs. (85±8)%,(39±15)% and (25±21)% vs. (62±16)%, all P < 0.05]. In newly-diagnosed DLBCL group, the absolute counts of CD3 + T and CD4 + T cells were negatively correlated with the proportion of effector Treg ( r = -0.379, P = 0.049; r = -0.384, P = 0.040, respectively). IPI score of DLBCL patients was correlated with the proportion of CD8 + T cells ( Eta2 = 0.15, P = 0.038). The proportion of CD127 + memory Tcon in patients with non-complete remission was increased compared with that in patients with complete remission after treatment ( P = 0.020). Conclusions:The proportion and absolute count of T lymphocyte cells in peripheral blood of newly-diagnosed DLBCL patients is decreased, and the differentiation state of T lymphocyte cells shows change trend, which is related to the clinical characteristics and treatment response of DLBCL patients. Even if DLBCL patients have achieved treatment remission, T lymphocyte cells are not completely return to the normal.