When asked how colds and other infections can be prevented, a wide variety of answers are usually given, such as a diet rich in antioxidants, regular exercise and immune-supporting supplements. If someone were to say that tattooing the skin could reduce the risk of infection, the person being interviewed would probably at least shake his or her head in disbelief and disgust - researchers from the University of Alabama, however, are convincing that, in some ways, tattoos really can have a beneficial effect on the human body's immunity.