MICROHETEROGENEITY OF ACUTE-PHASE GLYCOPROTEINS IN PATIENTS WITH PULMONARY SARCOIDOSIS

This study was designed to investigate qualitative changes in the carb ohydrate side-chains of two acute-phase glycoproteins, alpha(1)-acid g lycoprotein (AGP) and alpha(1)-antichymotrypsin (ACT), in 37 patients with pulmonary sarcoidosis. The glycosylation profile of AGP and ACT w as studied using affinity immuno- electrophoresis with the lectin conc anavalin A (conA). Serum concentration of soluble receptor for interle ukin-2 (sIL-2R) and activity of serum angiotensin converting enzyme (A CE) were measured by specific enzyme-linked immunosorbent assay (ELISA ) and enzyme kinetic assay, respectively. Rocket immunoelectrophoresis and nephelometric assay were used to determine serum concentration of AGP, ACT and C-reactive protein (CRP). In 11 patients with active dis ease, a decreased reactivity of AGP with conA was found as compared wi th controls (n=44) and patients with nonactive sarcoidosis (n=26). A s imilar tendency was seen with ACT. In the same group, increased concen trations of serum AGP and higher levels of sIL-2R were detected compar ed with patients with nonactive sarcoidosis. In the entire sarcoidosis group, there was a negative correlation between ACE activity and AGP and ACT affinity for conA (r=0.6358, and r=0.5019, respectively) and a positive correlation with sIL-2R level (r=0.8241). In nine patients w ith elevated concentrations of serum CRP, no differences were found in disease activity and glycosylation profile of AGP and ACT when compar ed to patients with normal serum CRP. The results suggest that in acti ve pulmonary sarcoidosis changes in the glycosylation pattern of acute -phase glycoproteins exist, which are similar in trend and magnitude t o those found in other chronic inflammatory diseases. The synthesis an d glycosylation of acute-phase proteins in pulmonary sarcoidosis are p robably regulated independently.