In vitro study of phenotypical characteristics of BCG granuloma macrophages over the course of granuloma development.

Structural and immunophenotypical characteristics of macrophages, associated with their polarization in the M1 and M2 directions of differentiation and activation, were studied in different morphological types of BCG granulomas by the expression of GM-CSF, IFN-γ, and FGFb cytokines and CD36 and CD16/32 differentiation clusters. The proportion of IFN-γ and FGFb macrophage subpopulations changed over the course of granuloma formation, which led to accumulation of FGFb macrophages in the granulomas. These data indicated that the formation of macrophage granulomas and their subsequent transformation into epithelioid-cell granulomas were associated with dynamic quantitative changes in the subpopulations of macrophages with the morphofunctional characteristics of M1 and M2 phenotypes, determining the antibacterial and destructive potential of granulomas. These data are useful for understanding the contribution of functional polarization of macrophages to the pathogenesis of tuberculous infection and, presumably, its complications.