Characteristics of PBMC obtained from leukapheresis products and tumor biopsies of patients with non-small cell lung cancer

Abstract

The current study characterized peripheral blood mononuclear cells (PBMC) obtained from leukapheresis products of patients with non-small cell lung cancer (NSCLC) for cytokine release, the ability to incorporate tritiated thymidine following stimulation using PHA as well as the levels of both CD4 and CD8 regulatory T cells (Tregs) as defined by FoxP3 expression. Results were compared to normal donor PBMC obtained from buffy coat products. Heterogeneous levels of Th1 (gamma interferon and IL-2), Th2 (IL-10 and IL-13), pro-inflammatory (TNF-alpha and IL-6) and the hematopoietic inducing cytokine GMCSF were detected from both populations of PBMC as measured using ELISA. Overall, we observed that combined levels of Th1 and Th2 cytokines were higher in lung cancer patients compared to that seen in normal donor PBMC. The increased cytokine production was coupled with an observed decrease in the ability of lung cancer patient PBMC to incorporate tritiated thymidine. Furthermore, cytokine containing supernatants obtained from patients inhibited the incorporation of tritiated thymidine from PBMC obtained from normal donors. Thus, the combined cytokines which included high levels of IL-10, appeared to exhibit suppressive functional activity. While not statistically significant, the overall trend toward a Th2 cytokine environment was supported by an increased level of Tregs observed in the leukapheresis products of lung cancer patients. These levels were variable and were accompanied by higher than normal levels of CD8+ cells co-expressing FoxP3. Finally, tumor biopsies were examined from lung cancer patients along with autologous normal adjacent tissue (NAT). In these studies, both gamma interferon and IL-10 were detected. The levels of IL-10 in the LPS stimulated cultures were statistically greater from the cancer biopsies compared to the NAT. The current study confirms many earlier results in a comprehensive manner and extends the analysis to leukapheresis products. An environment is described in cancer patients which is characterized by increased cytokine production and decreased proliferative potential likely under the influence of a significant population of regulatory T cells (Tregs). Taken together, these results are discussed as they relate to the potential implications in lung cancer patients immune response to their disease.