CD4 and bladder transitional cell carcinoma: An increased abundance of B cells, naive CD4+ T cells, naive CD8+ T cells, dendritic cells, exhausted T cells, gamma delta T cells, macrophages, monocytes, neutrophils, NK cells, natural regulatory T cells, and follicular helper T cells was proven to promote BLCA aggressiveness, and a reduced abundance of central memory T cells, effector memory T cells, mucosal-associated invariant T cells, NKT cells, T helper 17 cells, and T helper 2 cells was observed in the high-risk group, indicating a “hot” tumour immune microenvironment in BLCA tissues.