The prognostic role of circulating CD8+ T cell proliferation in patients with untreated extensive stage small cell lung cancer

Abstract

Background: Immunosuppression caused by tumorigenesis may promote tumor progress and invasion. Here, we investigated whether the characteristics of circulating T lymphocyte subtypes in patients with extensive small cell lung cancer (ED-SCLC) can be used as an alternative marker of tumor progression. Methods: This study included 36 newly diagnosed ED-SCLC patients before treatment and the patients were followed up. 22 age and sex-matched healthy volunteers were selected as control. The percentages and proliferation potential of T lymphocyte subpopulations from peripheral blood were measured. Results: CD4+ CD25+ Foxp3+ regulatory T cells (Tregs) were elevated in ED-SCLC patients compared with healthy controls (p = 0.0083). In contrast, the percentages of CD3+ and CD3+CD4+ T cells were significantly lower in SCLC patients (p < 0.001; p = 0.0014). The proliferation (%divided) of CD8+ T cells of SCLC patients was suppressed compared with healthy controls (p = 0.0058), but not of CD4+ T cells (p = 0.1611). Multivariate analyses showed that the %divided of CD8+ T cells is an independent predictor for PFS (HR: 4.342, 95% CI 1.324-14.245; p = 0.015). The percentages of peripheral Tregs and the degree of chemotherapy or radiotherapy induced lymphopenia negatively correlated with the proliferation of CD8+ T cells (p = 0.0225, r = - 0.379; p = 0.0003, r = - 0.464). Conclusion: The present study indicates that SCLC patients have impaired immunity in peripheral blood, and the proliferation potential of circulating CD8+ T cells is a significant predicator for PFS.