A Cross-Sectional Study of CD163 Expression and CD8-Positive Tumor-Infiltrating Lymphocytes in Glial Tumors at a...

Background and objective Glial tumors are increasingly recognized as immunologically active neoplasms in which macrophage-rich and lymphocyte-poor microenvironments may influence aggressiveness. Cluster of differentiation 163 (CD163) highlights tumor-associated macrophages, whereas CD8 marks cytotoxic tumor-infiltrating lymphocytes (TILs). This study aimed to evaluate CD163 expression and CD8-positive TILs in glial tumors and examine their association with tumor grade. Methods This cross-sectional study included 50 histopathologically confirmed glial tumors. Immunohistochemistry for CD163 and CD8 was performed on formalin-fixed paraffin-embedded tissue sections. CD163 was scored as absent, weak, moderate, or strong, and CD8 infiltration was categorized as low or high. Associations with World Health Organization (WHO) tumor grade and histologic aggressiveness were analyzed using the chi-square test, Fisher's exact test, and Spearman's correlation. Results The mean age of the cohort was 42.7 ± 16.1 years, with males accounting for 29/50 (58.0%) and females for 21/50 (42.0%). High-grade gliomas comprised 32/50 (64.0%) cases, while low-grade tumors accounted for 18/50 (36.0%); grade IV tumors were the largest subgroup (20/50, 40.0%). CD163 positivity was observed in 40/50 (80.0%) tumors and increased significantly with tumor grade (rho = +0.59, p < 0.001). CD163 positivity was more frequent in high-grade than in low-grade tumors (30/32 (93.8%) vs. 10/18 (55.6%), p = 0.004). High CD8 infiltration was seen in 15/50 (30.0%) tumors and low CD8 infiltration in 35/50 (70.0%), with CD8 levels declining significantly with increasing grade (rho = -0.33, p = 0.021). Strong CD163 expression with low CD8 infiltration was present in 17/50 (34.0%) tumors and was significantly associated with high-grade lesions (16/32 (50.0%) vs. 1/18 (5.6%), p = 0.004). Moderate-to-strong CD163 expression was associated with necrosis (18/20 (90.0%), p = 0.009) and microvascular proliferation (16/18 (88.9%), p = 0.024). Conclusions Higher-grade glial tumors demonstrate a macrophage-dominant and CD8-restricted immune microenvironment. Combined assessment of CD163 and CD8 may serve as a practical indicator of aggressive tumor biology in routine diagnostic practice.