Immunoassay with fluorescein-labelled antigens--device of a method and its clinical application.

A simple, sensitive, highly reproducible method for assay of antibodies using fluorescein-labelled antigens according to the method by Farr is described. We measured titers of anti-BSA antibodies and antigen binding capacity of sera in BSA immunized rabbits by fluorometric assay with fluorescein isothiocyanate (FITC) labelled BSA, and obtained highly reproducible and quantitative results. The resultd times more sensitive than the results from single radial immunodiffusion. FITC-labelled double or single stranded calf thymus DNA was incubated with sera of patients with systemic lupus erythematosus and New Zealand Black mice. Both anti-double and single stranded DNA antibodies were detected in sera of systemic lupus erythematosus, but only anti-single stranded DNA antibodies in sera of New Zealand Black mice.