CD4 and bladder transitional cell carcinoma: In BLCA, the correlation between the expression level of PCSK9 with immune cells was significant, including CD8+ T cells (R = 0.246, p = 1.82E−06), CD4+ T cells (R = 0.086, p = 9.93E−02), macrophages (R = 0.167, p = 1.35E−03), neutrophils (R = 0.231, p = 8.38E−06), and DCs (R = 0.356, p = 2.50E−12).