Tumor-infiltrating lymphocytes (TILs) have been shown to play a crucial role in cancer, both as a whole and their individual subpopulations. Here, the researchers analyzed the correlation between CD3+, CD8+, CD45RO+, and FOXP3+ TILs with patient survival and clinical and pathological features of bladder cancer. Tumor tissues from 85 patients with urothelial cell carcinoma of the bladder were analyzed immunohistochemically to determine the extent to which each subset had infiltrated the stroma and the tumor itself during their respective time periods of survival. Their data showed that the number of CD45RO+ lymphocytes present within high-grade tumors was considerably larger than that found within low-grade tumors (P=0.028). Muscle invasion was also associated with a higher frequency of intratumoral CD3+ (P=0.002), CD8+ (P=0.008), intratumoral (P=0.002), and stromal (P=0.017) CD45RO+ cells. There was also a difference in the frequencies of CD3+ (P=0.043), CD8+ (P=0.003), CD45RO+ (P=0.023), and total CD45RO+ (P = 0.015) cells within tumors between patients of different T-stages, with the former being primarily elevated in T2 compared to Ta and T1. Total CD3+ (P=0.011), intratumoral CD3+ (P=0.006), total CD8+ (P=0.012), intratumoral CD8+ (P=0.009), and stromal CD8+ (P=0.034), and total and stromal CD45RO+ lymphocytes (P=0.01 and P=0.034, respectively) were all higher in stage II patients than in stage I patients, while stromal CD3+ (P=0.077) and CD8+ (P=0.053). Overall, they found that early-stage tumours had a much higher frequency of immune cells, particularly CD45RO+, CD3+, and CD8+ lymphocytes. Their finding might be explained by an increase in the recruitment factors, particularly in the early stages, to destroy tumor cells or by the constant and extended activation of immune cells with tumor antigens throughout tumor formation. However, further functional investigations with bigger sample sizes are required to disclose the true condition of the immune system in patients with bladder cancer.

Source: bmcurol.biomedcentral.com/articles/10.1186/s12894-022-01085-6