Antigenicity and cross-reactivity of denatured fibril proteins of primary, secondary, and myeloma associated amyloids.

Antisera have been produced against amyloid fibril preparations of primary, secondary, and myeloma origins. These have revealed the presence of both idiotypic and shared antigenic determinants. A high degree of cross-reactivity among the 3 types of amyloid has been found irrespective of classification. One antiserum to a secondary amyloid fibril preparation proved to be directed against A protein (the major nonimmunoglobulin constituent of secondary amyloid fibrils). This antiserum detected A protein in several of the secondary amyloids as well as in two primary amyloid fibril preparations which were degraded with alkali; These finding indicate that amyloid fibrils of various origins have similarities in composition and, therefore, may have common factors involved in fibrillogenesis.