Peripheral Immune Alterations and Checkpoint Expression in Localized Clear Cell Renal Cell Carcinoma Before and AfterNephrectomy: A Prospective Cohort Study

<title>Abstract</title> <p> Background Clear cell renal cell carcinoma (ccRCC) induces systemic immune alterations that extend beyond the tumor microenvironment. However, the impact of nephrectomy on peripheral immune cell populations and immune checkpoint expression in localized disease remains incompletely understood. This study evaluated changes in circulating leukocytes, inflammatory indices, and immune checkpoint expression before and after nephrectomy in patients with localized ccRCC. Methods: Twenty patients with localized ccRCC undergoing nephrectomy and six age- and sex- matched healthy controls were prospectively enrolled. Peripheral blood samples were collected before surgery and at postoperative follow-up (3–6 months). Multiparametric flow cytometry was used to quantify leukocyte subsets and expression of PD-1, LAG-3, TIM-3, CTLA-4, and PD-L1. The neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation index (SII) were calculated from complete blood counts. Comparisons among groups were performed using the Kruskal-Wallis test followed by Bonferroni correction. Results: Patients with localized ccRCC exhibited significantly increased circulating neutrophils, CD8 ⁺ T cell frequencies, and NLR decreased toward control values, indicating partial resolution of tumor-associated systemic inflammation. Monocyte and lymphocyte frequencies, as well as PLR and SII, remained unchanged. Peripheral immune checkpoint profiling demonstrated persistently increased PD-1 and postoperative CTLA-4 expression, together with reduced PD-L1 expression, whereas LAG-3 and TIM-3 expression showed no significant changes. Conclusions: Localized ccRCC is associated with measurable systemic immune dysregulation characterized by neutrophilia, increased CD8 ⁺ T cells, elevated NLR, and altered immune checkpoint expression. Although nephrectomy partially reverses inflammatory changes, persistent checkpoint dysregulation suggests incomplete immune restoration. Peripheral immune profiling may represent a minimally invasive approach for monitoring systemic immune status in patients with localized ccRCC. </p>