Moving beyond the immune self?

We are witnessing a significant challenge to immunology's basic tenet, the immune self. Such an 'entity' is increasingly regarded as polymorphous and ill defined as transplantation biology and autoimmunity have demonstrated phenomena that fail to allow faithful adherence to a strict dichotomy of self/nonself discrimination. Instead of searching for elusive criteria of 'self' and 'other', immune responses are increasingly studied as arising within complex contexts, which determine various degrees of reactivity or dormancy. When the character of the immune 'object' is determined by the context in which it appears, not its character as 'foreign' per se, self/nonself discrimination recedes as a governing principle. In such context-based models, 'ecologic' controls arise from the entire organism in which the immune system is fully integrated. In these systems, subject-object relationships become blurred. Viewed from this perspective, a new theoretical construction of the immune system, one originally proposed by Jerne, is contending with Burnet's theory of immune identity. Although it is too early to judge which theory will prove more capacious, it is already apparent that Jerne's formulation has had a decisive impact in shaping new models of immunity.