Antinuclear antibodies defining autoimmunity pathways.

Immunofluorescent imaging has been a powerful technique in helping to identify intracellular nuclear and cytoplasmic molecules which are target antigens of autoantibodies in systemic autoimmune disorders. Patterns of staining can be correlated with molecules engaged in specific cellular functions and distributed in distinct cellular domains. Different autoimmune disorders have different profiles of autoantibodies, and immunodiagnostics has become an important adjunct in differential diagnosis. An important finding that has eluded explanation is the presence of autoantibodies to many different antigens, manifested strikingly in systemic lupus erythematosus. In cancer, the occurrence of autoantibodies to tumor-associated antigens is not uncommon and a characteristic feature is also the presence of multiple autoantibodies. The targeted tumor-associated antigens are either oncogene or tumor suppressor gene products or their coactivators, which are altered or mutated and driving the autoimmune response. Most cancer cells have between two and eight mutated genes before oncogenic transformation occurs, initiating a process called synthetic lethality in tumorigenesis pathways. These observations beg the question of whether there are similar mechanisms in systemic lupus erythematosus and other disorders driving autoimmunity pathways. Targeting molecules that are synthetic lethal to each other is in the forefront of the search for anticancer therapy, and this could also be an objective in systemic autoimmune disorders.