Intestinal macrophages and dendritic cells: what's the difference?

• Intestinal macrophages express CD64 and are constantly replenished by blood monocytes.
• Intestinal macrophages are anti-inflammatory, sessile, and maintain local homeostasis.
• Intestinal DCs derive from committed DC precursors in an flt3L-dependent manner.
• Four subsets of intestinal DCs exist, identified by CD103 and CD11b expression.
• DCs migrate to lymph nodes to prime naïve T cells. Subsets have discrete functions.

Mononuclear phagocytes (MPs) in the murine intestine, comprising dendritic cells (DCs) and macrophages (Mϕs), perform disparate yet complementary immunological functions. Functional analyses of these distinct MP subsets have been complicated by the substantial overlap in their surface phenotypes. Here, we review recent findings that have enabled more accurate definition of these MP subsets. We discuss these recent advances in the context of the current understanding of the functions of DCs and Mϕs in the maintenance of intestinal homeostasis, and how their functions may alter when homeostasis is disrupted.