Plasmacytoid dendritic cells: Key players in viral infections and autoimmune diseases

Objective

Describe the main activation and inhibitory pathways and receptors by which pDC regulate type I interferon secretion, as well as its association with autoimmune pathology.

Methods

A PubMed search for articles was conducted using the following key words: plasmacytoid dendritic cells, autoimmune diseases, viral infections and type I interferon. The search was limited to publications in English and from 1957 to 2012. Sixty-five of these articles are included in this review. The most relevant primary research articles identified were critically evaluated and compiled together. Particularly, areas of consensus and controversy were identified and analyzed.

Results

Plasmacytoid dendritic cells have been closely related to viral infections and autoimmune disease, mainly because of these immune cells are able to secrete large amounts of type I interferon. This function is linked with their expression of Toll-like receptors, specially TLR7 and TLR9, which are designed to sense nucleic acids in the early endosomes. Activated pDC can promote immunity and autoimmunity, however, the exact mechanisms by which pDC promote one vs. the other are not well understood.

Conclusions

Plasmacytoid dendritic cells play a key role in both, immunity and autoimmunity. Current evidence suggests that the sustained overproduction of type-I interferon drives aberrant immune responses and the development of autoimmune pathology.