Analysis of M1 and M2 tumor associated macrophages in tongue squamous cell carcinomas.

Tumor associated macrophages (TAMs) are the dominant leukocyte population found in the tumor microenvironment and their mobilization into tumor tissues is a critical event in tumor initiation, growth, and development. TAMs are a heterogeneous population of innate myeloid cells and take on various phenotypes depending on the context of the molecular stimuli from the microenvironment. Basically, there are two main recognized categories: classically-activated pro-inflammatory M1 macrophages (expressing the CD11c antigen) and alternatively-activated anti-inflammatory M2 macrophages (expressing the CD163 antigen). Although TAMs have been detected in head and neck cancers, little is known about their phenotype in the context of the tongue squamous cell carcinoma (TSCC), which have the highest incidence in maxillofacial malignant tumors. The aim of the present retrospective study was to characterize the macrophage polarization in low grade (G1) and high grade (G3) TSCC, and to examine the importance of their relative localization (tumor stroma, inflammation area or tumor nest) on tumor-promoting capabilities and tumor-prognostic relevance.