Variation with age and disease of an amyloid A protein-related serum component.

TLDR

A radioimmunoassay for serum amyloid A was developed using 125I‑labelled alkaline‑degraded acid‑soluble amyloid (DAA) as the antigen. Serum amyloid A was detected in all human sera (mean 94 ± 57 ng/ml), rising with age, markedly elevated in amyloidosis (except nephrotic syndrome) and in many malignancies, rheumatic disease, tuberculosis, and showing a rapid rise and fall during acute inflammation faster than ESR. The study discusses the potential role of serum amyloid A in amyloid formation and immune responses.

Abstract

Using the radioactively-labeled alkaline-degraded acid-soluble fraction of amyloid ([ 125I ]DAA), we developed a radioimmunoassay for the previously described amyloid-related component of the human serum (SAA). Screening the sera of 228 normal individuals and of 297 patients with a variety of illnesses, we found that SAA is a component of all human sera, including cord blood (mean 94 plus or minus 57 ng/ml). The concentration of this component increases significantly with the aging process, reaching very high levels in the eighth and nine decades. It is also elevated in all cases of amyloidosis (except for those associated with nephrotic syndrome) as well as in many patients with myeloma, macroglobulinemia, lymphoma, carcinoma, rheumatoid arthritis, and tuberculosis. A marked increase was noted in the early stages of a variety of acute inflammatory and infectious states with a return to normal levels paralleling clinical improvement and faster than the erythrocyte sedimentation rate. The possible implications of this component in the genesis of amyloid and in the immune process are discussed.