Surface expression of CTLA-4 on CD4/CD25 high cells in lung cancer

The impairment immune surveillance plays an important role in the progression of lung cancer. CTLA-4 and regulatory T cells (Treg) are essential for the control of immune homeostasis. CTLA-4 is constitutively expressed on Treg cells and plays significant role in the regulation of T cell tolerance, however CTLA-4 can also functions in the non-Treg compartment. The aim of this study was to analyze the population of CD4+⁄CD25+ and CD4+⁄CD25+ high cells-and expression of CTLA-4 in the peripheral blood (PB) of lung cancer patients. Many studies show that CD25+ high cells correspond with Treg, FoxP3 positive cells. Thirty patients with lung cancer (60% NSCLC and 40% SCLC) and ten healthy volunteers were investigated. Flow cytometry method with panel of monoclonal antibodies anti CD4⁄CD25⁄CTLA-4 were used. We observed a significantly higher proportion of CD4+⁄CD25+ and CD4+⁄CD25+ high cells in the group of patients with lung cancer than in healthy controls (15.1 vs 8.4% and 2.8 vs 1.8%, respectively, P <0.05) . The proportion of CTLA4 cells as a percentage of CD4+/CD25+ and CD4+/CD25+ high cells was significantly higher in the patients when compared with healthy persons (1.9 vs 0.9% and 6.7 vs 2.2%, respectively, P <0.05) and higher proportion of CD4+/CD25+/CTLA-4 in patients with distant metastasis than with regional advanced disease ( P= 0.009). The mean fluorescence of CTLA-4 on CD4+/CD25+ high cells in patient was higher than in controls (865% vs 580%). We did not find any correlation with clinical data nor number of pack/years. In conclusion we supported the significance of CTLA-4 expression on CD4+⁄CD25+ high cells in systemic immunosuppression in lung cancer. It may be useful in individual anti-CTLA-4 therapies.