Shared Gelsolin Antigenicity Between Familial Amyloidosis Finnish Type (FAF) and One form of Familial Lattice Corneal Dystrophy (LCD) with Polyneuropathy from the United States

Abstract

Amyloid may involve the cornea in sporadic and familial forms of LCD, as Polymorphic Amyloid Degeneration (PAD), primary gelatinous drop-like dystrophy or, in rare cases, as part of systemic light chain deposition. LCD is prominent in Familial Amyloidosis, Finnish type (FAF), clinical features of which have also been described in rare kindreds from the Netherlands, Denmark and the United States. Previous studies from our laboratories have found AP, but not AA, AL or prealbumin (transthyretin)-reactivity in cases of FAF, hereditary and sporadic LCD from the United States, and PAD examined immunohistologically and by Western Blot analysis of solubilized corneal proteins. Because we have now shown the FAF amyloid to be composed of a 12 kD internal fragment of plasma or cytoplasmic gelsolin, we sought to extend our previous observations using a rabbit antibody developed to the FAF subunit protein, and a commercially-available murine monoclonal antibody to plasma gelsolin. Anti-FAF reacted strongly in tissue section with amyloid deposits from Finnish patients in kidney and cornea, as well as with cornea, conjunctival and skin amyloid deposits from one previously described (Ophthalmology 9:1512, 1983) American case of Meretoja-type familial LCD. No reaction was obtained with cases of sporadic LCD (3), PAD (2) or drop dystrophy (1). The murine antibody, which is specific for a peptide that includes the carboxy terminal actin-binding site of gelsolin, also reacted with amyloid deposits in various tissues of FAF patients (Amer. J. Pathol. 136:1223-1228, 1990). Anti-gelsolin did not react with cases of AL, AA or prealbumin (TTr)-related amyloid in tissue section. It thus appears that sporadic LCD, PAD and drop dystrophy are antigenically distinct from FAF and at least one form of familial LCD; additional studies will be necessary to determine if the former are due to fibril formation involving other gelsolin epitopes, or are due to other amyloidogenic proteins.