Further study of fluorescent free-radical products in synovial fluid

Abstract

Fluorescence (Ex 340–370 nm, Em 430–470 nm) in synovial fluid is associated with three fractions; IgG, albumin and an unidentified fraction. Albumin possesses the majority of the fluorescence (70–75%) and its response to pH change suggest a Schiff base structure. The fluorescence associated with the IgG fraction, however, is probably due to the free-radical oxidation of tryptophan residues. In a preliminary study significantly higher levels of fluorescence were observed in the IgG (p p>0.001) fractions isolated from synovial fluids of patients with ‘inflammatory’ as compared to ‘non-inflammatory’ conditions.