Identification of amyloid A protein in a sporadic Muckle-Wells syndrome. N-terminal amino acid sequence after isolation from formalin-fixed tissue.

The amyloid of a patient (WAL) with a sporadic Muckle-Wells syndrome was analyzed in tissue sections and after it had been isolated from formalin-fixed tissue. The predominant amyloid fibril protein was the amyloid A (AA) type determined by the following criteria. (a) Only antiserum against protein AA gave a strong specific reaction, whereas the other antisera with specificity against amyloid of immunoglobulin origin, i.e., A-lambda and A-kappa, did not stain using the indirect immunoperoxidase technique on formalin-fixed, paraffin-embedded tissue sections. (b) In immunodiffusion, the predominant amyloid fibril protein from WAL isolated in pure form from formalin-fixed tissues precipitated in a line of identity with anti-AA and a purified and chemically identified protein AA from another patient. (c) Amyloid fibril protein from WAL had a molecular weight of 8000 to 9000 in sodium dodecyl sulfate polyacrylamide gel electrophoresis and, thus, is in the same range as the commonly found protein AA. (d) The N-terminal amino acid sequence analysis was that of protein AA. In addition to the pure amyloid fibril protein AA (WAL), proteins of higher molecular weights with AA-antigenic determinants were also isolated. These proteins may represent protein AA in a complex form or protein AA linked to other proteins. Since an inflammation is the most likely cause of amyloidosis complicating the Muckle-Wells syndrome an antiinflammatory therapy (as in other AA-type amyloidoses) is recommended.