The thin line between conventional dendritic cells (cDCs) and group 3 innate lymphoid cells (ILC3s) in the gut.

Dendritic cells (DCs) express major histocompatibility complex class II (MHC-II) and are best known for proficiently presenting antigens to T cells, thereby eliciting specific adaptive T cell responses. Moreover, conventional DCs are specifically adept at handling intestinal antigens. Relatively recent discoveries and investigations have proven the existence of a new group of innate lymphocytes that reside in tissues like the intestine. They lack specific antigen-receptors and can express MHC-II. These group 3 innate lymphoid cells (ILC3s) comprise a subset of heterogeneous innate lymphocytes that mirror the phenotype and functions of T-helper cells and act in the first line of defense. Considering that ILC3s are crucial for maintaining homeostasis of the intestinal mucosa and are found in niches alongside DCs, we herein describe the roles played by cDCs and ILC3s in the gut, highlighting the most recent studies. We discuss how these cells are alike and differ, constantly pointing out the thin, blurry line that separates cDCs and ILC3s.