Causal relationship between immune cells and bladder cancer: A bidirectional Mendelian randomization study.

Prior research has examined immune cell involvement in bladder cancer (BCa). This Mendelian randomization (MR) study investigated causal links between 731 immune cell traits and BCa risk, identifying potential immunotherapy targets. Immune cell data came from a Sardinian cohort (3757 individuals), and BCa data from genome-wide association studies. We used inverse variance weighting as the main analysis, with MR-Egger and weighted median methods for validation. Stability checks included sensitivity analyses. Sixteen immune traits (related to 4 immune signals: MFI, RC, AC, MP) showed significant BCa associations. Five increased risk (OR > 1, P < .05), while 11 were protective (OR < 1, P < .05). No reverse causality, heterogeneity, or horizontal pleiotropy was found (P > .05). This MR analysis demonstrates complex causal relationships between immune cell traits and BCa, offering new insights for immunotherapy and prevention.