Isolation and Analysis of Human Monocytes and Adipose Tissue Macrophages.

Monocytes and macrophages are cells of the innate immune system, existing in circulation and permeating every tissue of the human body. These cells represent the first responders to stress, and their inflammatory activation forms part of virtually every human disease. It is for these reasons that several approaches have been developed in order to phenotypically and functionally analyze these cells and their subpopulations. These inflammatory cells have been consistently demonstrated to undergo inflammatory polarization through the engagement of lipid-activated nuclear receptors, namely, through PPARs and LXRs, which regulate both lipid metabolism and inflammation. Quantitative and phenotypic analyses of monocytes and macrophages are largely dependent on cytometric tools and antibody-based labelling of membrane markers, while functional analyses apply a range of in vitro approaches coupled with secondary analyses of gene or cytokine expression. An important aspect of phenotypic and functional analyses is the purification, enrichment, or appropriate differentiation of biological materials, ensuring experimentation is carried out on monocytes and/or macrophages and not on other cell types occupying the same physical niches. This chapter will focus on the most common analytical approaches applied to the mononuclear phagocytic system, namely, circulating monocytes and adipose tissue macrophages.