Prognostic Impact of Peripheral Blood T-Cell Subsets at the Time of Diagnosis on Survival in Patients with Diffuse Large B-Cell Lymphoma

Introduction: The effects of lymphocyte subtypes, including helper (Th), natural killer (NK), and regulatory (Treg) cells, and other T-cell subtypes on treatment outcomes in diffuse large B-cell lymphoma (DLBCL) patients are not clearly established. Methods: Among 151 consecutive patients diagnosed with DLBCL, we collected peripheral blood samples at diagnosis from 91 patients who received at least 1 cycle of R-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab) chemotherapy and analyzed lymphocyte subsets by flow cytometry. Results: DLBCL patients had a higher proportion of CD4+CD25+ Treg (p < 0.001) and lower absolute lymphocyte count than those of healthy controls. Lymphopenia at diagnosis was associated with advanced-stage disease (p = 0.001), a high-intermediate/high-risk International Prognostic Index (IPI) (p < 0.001), and older age (p = 0.060). High-intermediate/high-risk IPI, high proportion of CD3+CD4+ Th cells, and extranodal site ≥2 correlated with unfavorable prognostic factors for survival. High proportion of Th cells was associated with fewer cytotoxic T cells and NK cells at the time of diagnosis. Conclusion: This study showed an association between circulating lymphocyte subsets including Th cells, Tregs, and NK cells and clinical outcomes in DLBCL; however, further confirmation is needed via prospective trials.