CD163 and CCR7 as markers for macrophage polarization in lung cancer microenvironment

Introduction: M2 macrophages are predominant in the immune infiltrates of resected tumours, but little is known about macrophage phenotype in the local lung cancer environment, which may be evaluated by bronchoalveolar lavage fluid (BALF).

Aim of the study: To find differences between BALF from lung affected by cancer (clBALF) and hlBALF from the opposite, healthy lung, as a control, from the same patient, regarding their individual macrophage polarization and their correlation with IL-10 and TGF-β.

Material and methods: Eighteen patients with confirmed lung cancer were investigated. Macrophage subtyping was performed by immunofluorescence with antibodies anti-CCR7 and CD163 (M1 and M2, respectively).

Results: We found five populations of macrophages: cells with a single reaction: only for CCR7+ or CD163+, a double reaction (CCR7+CD163+), cells with a stronger CD163 (CCR7_lowCD163+), and cells with a stronger CCR7 (CCR7+CD163_low). The main population in the clBALF was composed of cells with a phenotype similar to M2 (CCR7_lowCD163+), while in the hlBALF the predominating phenotype was the one similar to M1 (CCR7+CD163_low). The median proportion of TGF-β1 concentration was higher in the clBALF and hlBALF supernatant than in the serum.

Conclusions: In this study we confirmed the usefulness of the immunofluorescence method with CCR7 and CD163 in the evaluation of BALF macrophage polarization in lung cancer.