Use of horseradish peroxidase in identification of serum antibodies and immune complexes.

We made 202 examinations on specimens from 78 patients, to evaluate the application of horseradish peroxidase-labeled antisera as compared to fluorescein-labeled material in a clinical immunology laboratory. Various circulating and tissue-fixed antibodies were identified by both techniques. The horseradish peroxidase technique can be substituted for the fluorescein isothiocyanate method for the evaluation of anti-nuclear antibody and anti-mitochondrial antibody without loss of specificity or sensitivity. Although the results are comparable, fluorescein isothiocyanate appears to be slightly more sensitive in the detection of the other circulating and tissue-fixed human antibodies examined. Further refinements in preparation and technique could well lead to the fluorescein method being replaced by horseradish peroxidase staining in the future.