The use of subcutaneous fat tissue for amyloid typing by enzyme-linked immunosorbent assay.

The amyloidoses are biochemically heterogeneous diseases with pathophysiologic deposits of various proteins. The clinical course, prognosis, and therapy are different for each type of amyloidosis and, therefore, a type-specific diagnosis is demanded as early as possible. We describe a method for typing the most common systemic amyloidoses of AL, AA, and transthyretin types by enzyme-linked immunosorbent assay (ELISA), using abdominal wall subcutaneous fat biopsy specimens. The method was tested on 21 abdominal fat biopsy specimens that were sent to the laboratory. Of these, 15 contained amyloid that was successfully characterized in 14 cases. One specimen contained amyloid that did not react with any antisera used. The 6 specimens without amyloid gave no reaction in ELISA. The described ELISA method is reliable and easy to perform, and the tissue sample needed is obtained by minor surgery.