Activated Macrophages of Monocytic Origin Predominantly Express Proinflammatory Cytokine Genes, Whereas Kupffer Cells Predominantly Express Anti-Inflammatory Cytokine Genes.

In the central nervous system and in the liver, the macrophage populations are represented exclusively by descendants of the hematopoietic progenitor cells of the yolk sac. The reasons for such differential distribution of macrophages are not fully understood. We found that, as can be judged by corresponding changes in the expression of CD86 and CD163 markers, the transient macrophages of monocytic lineage are more sensitive to activating stimuli. The two macrophage populations have distinct patterns of gene expression, which is particularly noticeable for M1- and M2-associated genes. For instance, Kupffer cells more readily develop and longer maintain the elevated expression levels of , , and upon the activation; by contrast, the macrophages of monocytic lineage express , , and upon the activation. The obtained results allow us to conclude that the activated Kupffer cells of the liver are committed to M2 phenotype, whereas the activated monocyte-derived macrophages show a typical M1 behavior. These observations are likely to reflect the situation in the microenvironments.