Expression of IL-10 by CD8+ T Cells Is a Favorable Prognostic Factor in Non-Small Cell Lung Cancer

CD8+ T cells have a controversial role in controlling cancer growth depending on their phenotype. The aim of our study was to investigate the role of interleukin (IL)-10+ve CD8+ T regulatory cells on the progression and prognosis of non-small cell lung cancer (NSCLC). Tissue specimens from 64 smokers, who underwent surgical resection for NSCLC, were immunostained to quantify CD8+ T cells in cancer stroma and in cancer cell nest. Furthermore, double immunohistochemistry was used to identify and count IL-10+ve CD8+ T cells. Results were expressed as the number of CD8+ T cells/area and as the percentage of IL-10+ve CD8+ T cells/total CD8+ T cells. The percentage of IL-10+ve CD8+ T cells was higher in stage I as compared to stage II, III and IV NSCLC in cancer stroma (p=0.0005). Conversely, the number of CD8+ T cells was not different between stage I and stage II, III, IV of NSCLC both in cancer stroma and in cancer cell nest. CD8+ T regulatory cells expressing IL-10 were a significant independent predictor of early tumour stage (logistic model coefficient: p=0.0015). Furthermore, NSCLC patients with a higher percentage of IL-10+ve CD8+ T cells had a longer survival than those with a lower percentage (logrank: p=0.0386). In conclusion, the IL-10+ve CD8+ T cell regulatory phenotype seems to be associated with a favourable prognosis in non-small cell lung cancer