Enzyme-linked immunosorbent assay for detection of antibodies to extractable nuclear antigens in systemic lupus erythematosus, with nylon as solid phase.

In this enzyme-linked immunosorbent assay (ELISA) for detection of antibodies against extractable nuclear antigens (ENA) in sera of patients with systemic lupus erythematosus (SLE), nylon is used as solid phase for antigen binding instead of the commonly used polystyrene surface. Optimal conditions for activation of the nylon beads, antigen coating, and other relevant factors have been investigated. We compared the incidence of anti-ENA antibodies in SLE, using chromogenic and fluorogenic enzyme substrates. Of SLE patients, 54% were positive for anti-ENA antibodies when chromogenic substrate was used as compared with 68% for fluorogenic substrate. Antibody activity against Sm and RNP antigens was distinguished on the basis of ribonuclease sensitivity of the RNP antigen. The method described offers advantages such as decreased background activity, increased surface area, facility for prolonged storage of antigen-coated solid phase, and miniaturization of the assay.