To determine clinical significance of measuring blood levels of protein precursors of AA- and AL-amyloidosis - SAA and immunoglobulin free light chains (ILC), respectively.
SAA concentrations were studied with ELISA in 43 rheumatoid arthritis (RA) patients including complicated with reactive AA-amyloidosis (n = 31). Inflammation activity and its severity were studied (indices Li, richi, HAQ, DAS4). A modern quantitative nephelometric method Freelite estimated ILC levels in 31 patients with AL-amyloidosis.
Patients with RA complicated with AA-amyloidosis and free of it had a strong correlation between blood serum SAA concentration and activity of joint disease. Elevated SAA concentrations to 160 mg/l (normal 10 mg/l) were detected in many patients with clinical remission of the joint syndrome. Significal inhibition of AA-amyloidosis progression was seen only in SAA concentration drop under 60 mg/l. For AL-amyloidosis patients ILC fall by less than 3 normal value means a 6-time increase in chances of a favourable outcome.
Monitoring of blood levels of proteins precursors of AA- and AL-amyloidosis is a key factor in prognosis of the disease and treatment efficacy.