Background: B-cell lymphoma is a hematologic malignancy associated with B cell molecular pathways and immune microenvironment dysregulation. While immune checkpoint (IC) studies in solid tumors are extensive, their role in B-cell lymphomas, especially dynamic IC expression during treatment and real-world prognostic correlations, remains underexplored. To investigate the clinical significance of peripheral immune checkpoint profiling in B-cell lymphoma by examining their prognostic utility as biomarkers of disease progression and treatment outcomes, further extending to mechanistically characterize how these checkpoints interact with regulatory T cells and IL-10 to shape the immunosuppressive tumor microenvironment-a critical knowledge gap in lymphoma immunobiology with direct therapeutic implications.We examine IC expression on circulating T cells across disease stages in B-cell lymphoma patients, correlating it with Treg and IL-10 levels.

Methods: We analyzed 140 B-cell lymphoma patients retrospectively. PD-1, CTLA-4, LAG-3, and TIM-3 expression on CD4+/CD8+ T cells was measured by flow cytometry. To compare the peripheral blood CD4+ and CD8+ T cell surface immune checkpoint molecular expression levels in patients with B-cell lymphomas with different clinical characteristics: patients with primary inert versus aggressive B-cell lymphoma, patients with primary single/no extranodal involvement versus multiple extranodal involvement, and patients with complete remission (CR) versus relapsed progression (R/P) group after treatment, respectively. Treg proportions and IL-10 levels were correlated with IC expression.

Results: Diagnostic-Related Analysis: Aggressive B-cell lymphoma showed higher PD-1/CTLA-4/LAG-3/TIM-3 expression than indolent subtypes (all P<0.05). Multiple extranodal involvement patients also exhibited elevated ICs versus single/no involvement (all P<0.05). Prognostic-Related Analysis: In patients with relapse/progression (R/P), the expression of PD-1 on CD4⁺T cells was 26.1%, significantly higher than the 8.2% in patients with complete remission (CR) (P<0.001). The expression of PD-1 on CD8⁺T cells was 25.2%, also significantly higher than the 7.1% in CR patients (P<0.001). Moreover, the expression levels of CTLA-4, LAG-3, and TIM-3 were higher in R/P patients than in CR patients (all P<0.05). ROC curve analysis was performed to evaluate the prognostic predictive value of immune checkpoint molecules on peripheral blood T cells in R/P and CR patients. PD-1/CTLA-4 showed prognostic predictive value (AUC>0.7 for CD4⁺/CD8⁺ T cells, all P<0.05), unlike LAG-3/TIM-3 (AUC<0.7). Tregs and IL-10 Level Analysis: A comparison of the proportion of Tregs and IL-10 levels in the peripheral blood of B-cell lymphoma patients (including both indolent B-cell lymphoma and DLBCL patients) between the CR group and the R/P group after treatment revealed that the proportion of Tregs in the R/P group (7.84%) was significantly higher than that in the CR group (3.58%, P<0.0001). Meanwhile, the IL-10 level in the R/P group (10.5 pg/mL) was also significantly higher than that in the CR group (5.44 pg/mL, P<0.0001), and this trend was confirmed in both indolent B-cell lymphoma and DLBCL subtypes (both P<0.05). Correlation Analysis: The correlation analysis between the proportion of Tregs and IL-10 levels in the peripheral blood of B-cell lymphoma patients and the expression levels of immune checkpoint molecules on T cells showed that the proportion of Tregs in peripheral blood was positively correlated with the expression level of PD-1 on CD4⁺T cells (r=0.539, P<0.0001). Similarly, the level of IL-10 in peripheral blood was positively correlated with the expression level of PD-1 on CD4⁺T cells (r=0.457, P<0.0001), but no significant correlation was found with other immune checkpoint molecules.

Conclusion: Peripheral T-cell immune checkpoints (especially PD-1/CTLA-4) correlate with B-cell lymphoma prognosis. The expression of PD-1 on CD4+ T cells is positively correlated with the proportion of Tregs and the level of IL-10, which may lead to immune microenvironmental dysregulation and disease progression by promoting the transformation of Tregs and secretion of IL-10, and activating the JAK2/STAT3 pathway in tumor cells. These findings provide new insights into the immune evasion mechanisms of B-cell lymphoma and offer a theoretical basis for the development of new therapeutic targets and prognostic markers.

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2025
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