Presence of tumour-infiltrating FOXP3+ lymphocytes correlates with immature tumour angiogenesis in renal cell carcinomas.

Background: FOXP3+ regulatory T cells (Tregs) inhibit effector T cell functions and are implicated in tumour progression. However, together with microvessel density (MVD) they remain controversial prognostic predictors for renal cell carcinoma (RCC), and potential associations have yet to be determined. The objective of this study was to determine the prognostic significance of Tregs and MVD and their potential relationship in RCCs.

Design: Paraffin-embedded tissues from 62 RCC patients were analysed using immunohistochemistry to detect FOXP3+ lymphocytes, and double immunohistochemistry to detect different microvessel types in the tumour interior, rim and normal kidney tissue, and their correlation with clinicopathological characteristics. Survival analysis was also performed.

Results: The presence of FOXP3+ cells in the tumour interior or the rim showed no correlation with death from RCC and other pathological characteristics. Negative correlations were noted between the immature MVD in the tumour interior or the rim and tumour size, tumour stage and overall survival; however, there was no correlation with the nuclear grade or pathological type. A positive correlation between FOXP3+ Tregs and immature MVD (r=0.363, P=0.014) and mature MVD (r=0.383, P=0.009) was confirmed in the tumour interior. However, there was no correlation between FOXP3+ Tregs and mature MVD (r=0.281, P=0.076) or immature MVD (r=0.064, P=0.692) in the tumour rim.

Conclusions: In this study, a positive correlation between the presence of FOXP3+ Tregs and immature and mature MVD in RCC was confirmed, which suggests a link between suppression of immunity, tumour angiogenesis and poor prognosis.