Antibodies to different components of the extractable nuclear antigen (ENA) have been thought to be serological markers for clinical subsets of rheumatic diseases. However, incomplete characterization and standardization of antigenic components such as ribonucleoprotein (RNP), Sm, and SS-B (Ha), and the multiplicity of autoantibodies produced by different patients have confounded correlations between autoantibody specificity and disease subsets. This study describes the preparative separation of the antigens Sm, RNP, and Ss-B (Ha) by electrofocusing and their use in a rocket electrophoretic assay that in one step identifies and quantifies the multiple reactivities of patient sera exhibiting the speckled FANA pattern. Preparative electrofocusing generates milligram quantities of these antigens with retention of their immunologic and biochemical characteristics, facilitating further study of their biological properties and relationships to disease subsets.
T B Okarma, J A Krueger, H R Holman