The coexistence of systemic lupus erythematosus with other autoimmune diseases: the kaleidoscope of autoimmunity.

Patients with systemic lupus erythematosis (SLE) often manifest features of other autoimmune diseases. In this review, we provide a detailed compendium of features of SLE that overlap with other conditions. This compendium is important because a critical feature in our understanding of autoimmunity has been the clustering of coexisting/different autoimmune diseases both within an affected patient and within a pedigree. Indeed, autoimmune disorders share a variety of similar clinical and serological defects. For example, all autoimmune disorders are associated with the elaboration of autoantibodies and/or the production of self-reactive mononuclear cell populations; many have high levels of immune complexes and defects in cell-mediated immunity. Several diseases share similar genetic backgrounds, as reflected by study of loci within the major histocompatibility complex. In part the coassociation is due to common genetic tendencies with different environmental precipitating agents (trigger mechanisms). It is likely that many factors can modulate the immune system to autoimmunity in the presence of an appropriate genetic background, eg, drugs, viral infections, UV irradiation, and toxins, ie, toxic oil syndrome and L-tryptophan-induced eosinophilic myalgia. The coexistence of SLE with other autoimmune diseases is an excellent venue to understand these events, and we believe that the presence of other autoimmune diseases in patients with SLE can be called the kaleidoscope of autoimmunity.