Adaptable innate killers

摘要

Contact dermatitis is an occupational hazard for many people, This disruptive immune reaction can be caused by contact with an odd assortment of items, including plants, drugs, chemicals and even money. In each case, small, reactive molecules from theitem penetrate the skin and modify proteins within the tissue. Thus altered, the skin proteins are seen as foreign by the immune system, which then endeavours to destroy them. This dermatitis is caused by an adaptive response: the reaction occurs only if that specific antigen has been encountered before, and it is mediated by the archetypal white blood cells, or lymphocytes, of adaptive immunity - activated antigen-specific alpha bate T cells. In contact sensitivity, the mouse experimental model of contact dermatitis, three other types of lymphocyte are implicated in the reaction: B-l B cells, NK T cells and gamma delta T cells. These cells are part of the fast-acting defences of innate immunity, which do not strengthen with successive exposures to the antigen,. Notably absent from this list is the natural killer cell. So the report by O'Leary et al. in Nature Immunology is unexpected. They find that in mice lacking all other lymphocytes, natural killer cells play all the roles necessary to produce contact sensitivity.