Immunoassay of P-Component in Amyloidotic Sera. ∗

To date, all human amylodotic spleens studied by us have yielded a protein which is not detectable in normal or non-amyloidotic tissue. This protein has been identified by immunoelectrophoresis in the blood of normal individuals and for this reason has been called the P (plasma)—component of amyloid(1,2). We have recently measured the plasma level of P-component in patients with amyloidosis in order to determine whether its presence has any diagnostic significance and whether any data relevant to the genesis of amyloid might be obtained. Sera from patients with rheumatoid arthritis were studied as “pathologic” controls and also because this condition is not infrequently complicated by amyloidosis.

Materials and Methods. A total of 35 pathologic sera were tested; 21 were derived from patients with biopsy proven amyloidosis, the remaining 14 from patients with classical rheumatoid arthritis. As controls, sera from 25 young and presumably healthy blood donors and cord blood from 9 new-born infants were tested. Serum was stored at —30°C and thawed just before use. An antiserum specific for P-component was prepared in rabbits from extracts of amyloid-laden tissues as previously described(3).