Treatment of alopecia areata: "What is new on the horizon?".

New drug treatment opportunities based on the results of a genome-wide association study, which implicate T cell and natural killer (NK)-cell activation pathways, are leading to new approaches in future clinical trials of alopecia areata. Special attention is being given to the UL 16-binding protein (ULBP3) gene cluster on chromosome 6q25, as these genes make the NKG2D-activating ligand or signal that can trigger the NKG2D receptor, initiating an autoimmune response. A greater expression of ULBP3 has also been found in hair follicles in scalp biopsy specimens from patients with active disease. It is now postulated that the characteristic T cell "swarm of bees" infiltrate seen in alopecia areata is the result of T cells being attracted to the hair follicle by NKG2D-activating ligands. Future treatment approaches for alopecia areata include use of drugs that: (i) block the NKGD-activating ligand and NKG2D receptor interaction, (ii) halt activated T cells, or (iii) modification of the inflammatory cytokine network. Many drugs currently being used or being evaluated for other autoimmune diseases that work through these mechanisms might prove to be very effective in alopecia areata.