The traditional function of natural killer (NK) cells and their role in atopic dermatitis (AD), alopecia areata (AA) and pemphigus vulgaris (PV) was reviewed. NK cells are a type of lymphocyte that actively participates in the modulation of both innate and adaptive immunity. In patients with allergic conditions T-helper cell 2 (Th2) cytokine production by NK cells is a contributory factor. In psoriasis NK cells are involved in the production of interferon gamma; NK cell overactivation is a feature of AA and PV. Much remains to be learned about NK cells, but they are more widely involved than hitherto believed in many disease areas (von Bubnoff, D. et al. J ...