A new type of immune cell that is dedicated to combating skin infections is identified in two papers published online in this week's Nature Immunology. The work could potentially prove useful in the development of treatments for skin conditions such as psoriasis and atopic dermatitis.

Specialized cells, known as TH-22 cells, have been identified which release a chemical mediator called interleukin 22 (IL-22) that has previously been linked to skin inflammation and wound healing. Teams led by Federica Sallusto and Hergen Spits both show that these TH-22 cells express receptors CCR6, CCR4 and CCR10 that direct the cells to the skin. Federica Sallusto and colleagues further show TH-22 cells are generated by unique immune presenting cells called plasmacytoid cells via the release of chemical mediators called IL-6 and groups of certain signaling molecules.

Both authors suggest a vicious cycle can arise if these TH-22 cells are remain switched on and might contribute to skin diseases such as psoriasis and atopic dermatitis.