How killer cells remember

Adaptive immune cells like B and T cells aren't the only players in the immune system that can recognize antigens months after initially responding to them. A linkurl:study published online;http://www.nature.com/nature/journal/vaop/ncurrent/full/nature07665.html in Nature today identifies a specific ligand-receptor interaction through which natural killer cells, part of the innate immune system and the body's first line of defense against immune invaders, remember and recognize antigens in the long-term. The study, led by linkurl:Lewis Lanier;http://microbiology.ucsf.edu/micro/faculty/Lanier/home.html at the University of California, San Francisco, traced mouse natural killer (NK) cells that had a receptor for cytomegalovirus, monitoring cell populations during and after the mice were infected with the virus. The researchers discovered that, after the initial infection, where NK cells proliferated 1000-fold in the spleen and liver, the cells persisted in the immune organs for several months. Further, when those NK cells were injected into a new mouse, which was then infected with the virus,...