Association between B7-H1 expression and bladder cancer: a meta-analysis.

B7 homolog 1 (B7-H1), which is also known as programmed death-L1, is an important member of the B7/CD28 costimulatory factor superfamily, which are emerging as important mediators of various host immune responses. B7-H1 is differentially expressed in various cell subsets and to different extents in human and murine cells. Human B7-H1 is constitutively expressed at low levels in dendritic cells and activated T cells (compared with high expression in activated murine T cells) and is highly expressed in monocytes and tumor cells. We conducted a meta-analysis to explore the association between B7-H1 expression and bladder cancer risk. Two groups were examined, including 352 bladder cancer cases and 60 healthy controls. Meta-analysis results revealed that B7-H1 expression is positively associated with bladder cancer and is strongly associated with the clinical stage of bladder cancer. However, no significant difference was found with respect to gender and the pathological grade of bladder cancer.