CD4⁺ctla-4⁺ t Lymphocytes Inversely Correlate With CD4⁺CD127⁺ T Cells In Brazilian Patients With Classical Hodgkin Lymphoma

CD4⁺CTLA-4⁺ T lymphocytes has long been recognized as regulatory T cells, potentially decreasing antitumor immune response. Augmentation of the immune response via blockade of CTLA-4 has shown an improvement in survival for patients with metastatic melanoma, which prompted the Food and Drug Administration (FDA) approval of the CTLA-4 function blocking antibody Ipilimumab for this disease. CD4⁺CD127⁺ T lymphocytes also participate in immune homeostasis and T-cell development. The increased expression of this marker on CD4⁺ T cells is associated with a effector phenotype. CD127-mediated signaling in human leukemia T-cells that may be of therapeutic value, namely regarding the potential use of PI3K and mTOR pharmacological inhibitors. Increased frequencies of regulatory CD4⁺ cells, together with decreased effector CD4⁺ cells in the tumor microenvironment and peripheral blood have been proposed as one of the mechanisms for the immunosuppression state observed in classical Hodgkin lymphoma (cHL) patients. However, little is known about CD4+ T cells subsets in patients with classical Hodgkin lymphoma (cHL) and how treatment can modify these cells.

The aim of the study was to evaluate the surface expression of CTLA-4 and CD127 on CD4⁺ T cells in peripheral blood mononuclear cells (PBMC) of patients with classical Hodgkin lymphoma (cHL) at diagnosis and post-treatment and correlate these findings with clinical and epidemiological aspects.

This is an open multicentric study and, so far, we included 54 patients from december 2009 to July 2013. Thirty-four patients have completed therapy until July 2012 and were included in this study. Blood was drawn at diagnosis and post-treatment (1 to 4 months after completion of therapy). The T cell phenotype was evaluated by flow cytometry using CD3, CD4, CD8, CTLA-4 and CD127 and correlated to phenotypic and clinical parameters in uni- and multivariate models pre and post-treatment. Nineteen healthy blood donors volunteers were recruited as controls. In this study, only cHL patients whose histology could be confirmed and Epstein-Barr (EBV) association established were studied. All patients were HIV negative and received ABVD chemotherapy protocol and radiotherapy if necessary.

From the 34 cHL patients recruited for this study, 17 (50%) were male, 16 (47%) had Epstein-Barr virus (EBV) related cHL, 27 (79%) patients presented with B symptoms and 18 (53%) patients had advanced diseases at diagnosis. The percentage of CD4+ T cells with CTLA-4 surface expression was significantly increased in patients with cHL at diagnosis compared with healthy controls (median 8.7 (0.8 - 30.3) vs 2.5 (0.7 - 11.2); P<0.001). Additionally, CD4⁺CTLA-4⁺ T lymphocytes significantly decreased following treatment (8.7 (0.8 - 30.3) vs 3.9 (0.8 - 10.3); p=0.01), with values similar to healthy controls (3.9 vs 2.5; p=0.42). By contrast, CD4⁺CD127⁺ T lymphocytes were decreased at diagnosis, with values increasing after therapy (41.2 (3.3 – 75.7) vs 54.9 (17.1 – 81.3); p=0.002), similar to healthy controls (54.9 (17.1 – 81.3) vs 58.2 (41.2 – 89.8); p=0.21). The expression of CD127 on CD4⁺ T cells negative correlated with the expression of CTLA-4 (p<0.001). In this study, these CD4⁺ T cells subpopulations were neither associated with treatment response nor relapse. The frequencies of these cells were not correlated with age, gender, disease stage, erythrocyte sedimentation rate (ESR), albumin levels and EBV status.

In this study we showed a negative correlation between CTLA-4 expression on CD4⁺ T cells with the expression of CD127 at diagnosis of patients with cHL. These results suggest a role of CTLA-4 and CD127 on Hodgkin lymphomagenesis, possibly negatively regulating host anti-tumor immune response. Further studies investigating these CD4⁺ T lymphocytes subpopulations with functional assays are warranted. The promising immunotherapy regimen targeting CTLA-4 and the use of drugs that alter CD127 signaling might be beneficial in classical Hodgkin lymphoma.

No relevant conflicts of interest to declare.