Detection of anti-Ro(SSA) antibodies by gel double diffusion and a 'sandwich' ELISA in systemic and subacute cutaneous lupus erythematosus and Sjögren's syndrome.

A newly described Ro 'sandwich' ELISA was compared to the gel double diffusion technique to detect anti-Ro(SSA) antibodies in Sjögren's syndrome, systemic and subacute cutaneous lupus erythematosus patients. This study demonstrates that the ELISA assay increased the frequency of detection of anti-Ro(SSA) antibodies in these well defined connective tissue disease patients by approximately 5-10% compared to the gel double diffusion anti-Ro(SSA) antibody assay. The study also confirms that some patients make anti-Ro(SSA) antibodies directed solely at unique human Ro(SSA) antigen epitopes. We also detected the existence of a significant Sjögren's syndrome patient population failing to make significant anti-Ro(SSA) antibodies. We conclude from our study that the gel double-diffusion technique employing human spleen extract as a source of the Ro(SSA) antigen is, at present, the most cost-effective test to detect anti-Ro(SSA) antibodies.