Skin resident T cells Implications for immune homeostasis and disease

A population of memory T cells stay resident (T_RM) at all times in peripheral tissues, such as the skin. These T_RM cells function as alarming sensors, cytotoxic killers and provide a long-term local memory that can spread widely when re-infected with the same antigen. However, when dysfunctional, skin located T_RM cells can have a profound role in various skin disorders, including psoriasis and vitiligo. T_RM cell-mediated skin disorders often show lesions with fixed cut-offs from healthy skin. Typically, these lesions resolve when treated, but tend to recur at the exact same location when treatment is discontinued. In the context of transplantation, T_RM cells can react to allogeneic cells promoting tissue inflammation. Targeting T_RM cells could lead to efficient treatment for these skin disorders. Yet, we still lack therapies capable of affecting only T_RM cells. Phototherapy is perhaps the most ancient form of treatment in dermatology, but remains a valuable treatment option for T_RM-associated diseases. More research has to be done on safety of blocking and inducing T_RM cells in human. Thankfully, novel research technologies and methodologies are emerging. Much can be learned about this new subset of T cells. Using this knowledge in therapeutic and preventive therapy development could lead to a better quality of life of many patients suffering from skin disorders.