TOLERANCE, DANGER, AND THE EXTENDED FAMILY

For many years immunologists have been well served by the viewpoint th at the immune system's primary goal is to discriminate between self an d non-self. I believe that it is time to change viewpoints and, in thi s essay, I discuss the possibility that the immune system does not car e about self and non-self, that its primary driving force is the need to detect and protect against danger, and that it does not do the job alone, but receives positive and negative communications from an exten ded network of other bodily tissues.