Our previous report showed that IgG levels are strongly correlated with the indocyanine green (ICG) retention rate in patients with liver cirrhosis (LC). This correlation suggests that hyperglobulinemia in LC could be explained by impairment of hepatic removal function. To estimate IgG turnover in LC, in the present paper was determined the advanced glycation end-products (AGE) on IgG as a marker of half-life.
Serum samples were obtained from patients with LC, rheumatoid arthritis (RA), and Sjögren syndrome (SjS), and from age-matched control patients. IgG was purified from serum by the protein G-based affinity method, concentrated by filtration, and used for assay of Nepsilon-(carboxymethyl) lysine (CML), a predominant AGE, by ELISA.
CML on IgG was significantly lower in patients with LC than in control patients, whereas there was no significant difference in total serum CML levels among patients with LC, RA, and SjS, and control patients. CML levels on IgG were negatively correlated with serum IgG levels in patients with LC, RA, and Sjögren syndrome SjS.
Based on these findings, it is suggested that IgG turnover is not likely to be prolonged but rather may be shortened in LC It may be concluded that, hyperglobulinemia is primarily caused by enhanced synthesis followed by up-regulation of catabolism of immunoglobulins.