Suppression of response to foreign substances by intestinal macrophages.

Macrophages play an important role in the maintenance of homeostasis by changing their function according to the tissue and environment everywhere in the body. We have proposed that intestinal macrophages, which exist in the front line receiving environmental information, have an important function in forming a macrophage network for biophylaxis. In this review, we introduce intestinal macrophages as an example of the highly plastic and flexible cells adaptable to environmental information. Intestinal macrophages are hyporesponsiveness to foreign substances, especially lipopolysaccharide (LPS), and less expression of CD14 and TLR4/MD-2, receptors for LPS. However, those proteins expression was observed in the cytoplasm of intestinal macrophage. We also found that intestinal macrophages treated with IgA could restore in response to LPS. In conclusion, intestinal macrophages possess the plasticity to respond sensitively to change in their environment and are considered to be involved inflammatory bowel disease development.