The amyloidosis of juvenile rheumatoid arthritis--comparative studies in Polish and American children. I. Levels of serum SAA protein.

Serum SAA concentration was determined by radioimmunoassay in 21 Polish children with amyloidosis secondary to juvenile rheumatoid arthritis (JRA). The results were compared to controls and children with JRA in Polish populations (where amyloidosis is a frequent complication of JRA) as well as to American children with JRA (where amyloidosis in JRA has been observed only sporadically) and American control children. No significant differences of SAA protein levels were found in the amyloidotic Polish children when compared to JRA Polish and American children. However, significantly higher levels of SAA protein were present in amyloidotic Polish children when compared to the control Polish and American group. High serum SAA protein concentration in JRA children did not necessarily correlate with the presence of secondary amyloidosis. Other mechanisms are probably involved in the development of amyloidosis.