Antinuclear antibodies in routine analysis: the relevance of putative clinical associations

Defined antinuclear antibodies (ANA), such as antibodies to Ro/SS-A, La/SS-B, Sm, and nRNP, are often present in serum samples from patients with systemic lupus erythematosus (SLE) or other connective tissue diseases (CTD). Most data on associations between the presence of these antibodies and defined disease features have been obtained with the use of predefined groups of patients. In this work the issue of disease associations was approached from a different angle: patients suspected of having CTD were selected on the presence of these ANA in their serum samples and clinical data were subsequently scored according to a defined protocol. It was then tried to relate measured ANA and clinical symptoms. No correlation was observed between the presence of antibodies to Ro/SS-A and specific clinical symptoms. The presence of antibodies to La/SS-B was associated with the diagnosis of Sjögren's syndrome combined with leukocytopenia. In patients positive for antibodies to Sm a significantly increased incidence of skin lesions, such as butterfly rashes and discoid lesions, was seen, together with signs of myocarditis. Myocarditis was also found to be associated with the presence of antibodies to nRNP. The data presented in this study show that previously reported associations of these ANA with clinical symptoms are not confirmed when unselected patients are used.