Evaluation of the phenotype pattern of macrophages isolated from malignant and non-malignant pleural effusions

Macrophages are among the infiltrate components of most malignant tumors. Tumor-associated macrophages (TAMs) may secrete a variety of humoral factors, which promote or inhibit tumor growth. In general, depending on their activation pathway, macrophages exhibit two different patterns of phenotype, M1 or M2. It is assumed that TAMs comprise pattern M2. In the malignant pleural effusion, macrophages are a frequent component of cytological evaluation. In this microenvironment, TAMs could be involved in the development of immunity. The phenotype of macrophages represented in malignant and non-malignant pleural effusions is unknown. In this study, macrophages were isolated from 38 pleural effusions (15 malignant and 23 non-malignant) and the expression of a variety of immune mediators and their receptors was assessed to determine the type of activation (M1 vs. M2). The expression of mRNA was analyzed for IL-1β, IL-4, IL-6, IL-10, IL-11, IL-18, TNFα, TGFβ1, IL1R1, IL1RAP, TLR2, TLR4, VLA4, CD62L, MMP2, MMP9, VEGFA, PDGFA, and PDGFB. In immunohistochemical evaluation, the expressions of CD68, mesothelin, MAC387, IL-1β, IL-6, IL-10, IL-12, TNFα, and CD105 were assessed. The cytoplasmic expression of IFNγ, TNFα, IL-6, and IL-10 and the surface expression of CD11a, CD14, CD15, CD16, CD23, CD25, CD45, CD54, CD62L, CD69, VLA2, VLA3, VLA4, VLA6, TLR2, TLR4, and CCR7 were tested using flow cytometry. In supernatants from macrophages cultures, TNFα, IL-1β, IL-6, IL-8, IL-10, IL-12, MCP1, and VEGF were investigated by cytometric beads array method (CBA flex sets) and TGFβ1 by ELISA. Our results indicate that macrophages from malignant and non-malignant pleural effusions differ from each other and suggest that macrophages isolated from non-malignant effusions show a pattern comparable to M1 while those isolated from malignant effusions express similarity to M2 phenotype, but they have not shown a classical M2 pattern.