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Lymphocyte apoptosis plays a crucial role in tumor-induced immunosuppression. Programmed death ligand-1 (PD-L1) blocks lymphocyte activation via its receptor, PD-1. However, PD-L1/PD-1 expression and its role in enhancing immune suppression in non-Hodgkin lymphoma (NHL) have not been identified. The purpose of the study was to assess PD-L1/PD-1 expression in circulating lymphocytes in NHL and its role in immunosuppression. Twenty newly diagnosed NHL patients and twenty normal volunteers were enrolled in the study. PD-L1/PD-1 expression in circulating lymphocytes and the apoptosis of lymphocyte subsets were assessed using flow cytometry. The findings revealed that the PD-L1 expression in circulating CD3+, CD3+CD4+, CD3+CD8+, and CD20+ lymphocytes were dramatically upregulated in NHL patients (p < 0.001), whereas peripheral lymphocytes expressed low levels of PD-1. Compared with normal volunteers, a significant increase in lymphocyte apoptosis was revealed by annexin-V binding on T and B lymphocytes (p < 0.001). Peripheral lymphocytes expressing PD-L1 were four times more vulnerable to apoptosis than those expressing PD-1. Our findings imply that PD-L1 upregulation contributes to NHL development by promoting circulating lymphocyte apoptosis. This research adds to our understanding of the function of the PD-L1/PD-1 pathway in tumor evasion, establishing a novel therapeutic target in NHL. The results offer additional evidence for the immunomodulatory role of PD-L1 in circulating lymphocytes, providing a rationale for further investigations into immunological dysfunctions resulting from NHL. PD-L1+ lymphocytes could be employed as a biomarker to assess the effectiveness of immune systems and predict illness in patients with NHL.

Tumor-infiltrating lymphocytes (TILs) correlate with the number and size of the surrounding lymph nodes in patients with colorectal carcinoma (CRC) and reflect the quality of the antitumor immune response. In this prospective study, we analyzed whether this response correlated with the circulating lymphocytes in peripheral blood (PB). In 47 patients with newly diagnosed CRC, flow cytometry was performed to analyze the B cells, T cells, NK cells, and a variety of their subsets in PB. The results were correlated with TILs in the resected tumor and with the number and size of the surrounding lymph nodes in nodal negative (N- patients (LN5: number of lymph nodes measuring ≥5 mm) and the metastasis-to-lymph node size ratio (MSR) in nodal positive patients (N+). Differences between the number of TILs could be seen between N+ and N- patients, dependent on the LN5 and MSR categories, with higher values in N- cases and in patients with a higher LN5 category or a lower MSR. Additionally, higher values of various circulating lymphocyte subgroups were observed in these patients. For the total PB lymphocytes, CD8 cells, and some of their subgroups, a positive correlation with the TILs was found. This study shows that circulating lymphocytes—in particular, cytotoxic T cells—correlate with the local antitumor immune response displayed by TILs and lymph node activation. Our findings indicate that local and generalized antitumor immune responses are concordant with their different components.