Monocytes and macrophages are the first defenses against pathogens and take part in the regulation of adaptive immune response. Circulating monocytes enter injured and inflamed peripheral tissues where they differentiate into different types of resident macrophages. As for T helper cells (Th), macrophages are classified into two categories: type 1 macrophages, which are classically activated (M1), and type 2 macrophages that are activated in a more specific way.
M1 macrophages are characterized by a proinflammatory phenotype and an anti-microbial activity. M2 macrophages are involved in angiogenesis, reparation as well as in the matrix remodeling process.
This in vitro assay is performed on M1 macrophages, in order to evaluate the capacity of compounds to induce a phenotype change (switch) of M2 macrophages into M1 macrophages. This assay evaluates, using flow cytometry, the release of pro-inflammatory cytokines (TNF-alpha, IL-6 and/or IL12p70) and/or the expression of CD80 and CD163 markers, respectively described as M1 polarity and M2 polarity markers.