Background The first reports on the differences in glycosylation, which may negatively affect the antibody function, came from the studies on rheumatoid arthritis (RA), and specifically, the occurrence of glycoform G0 (no galactose) . The increase of agalactosylated IgG in patients with other diseases (juvenile arthritis, Crohn’s disease)  was also found. It is known, that the percentage of IgG agalactosyled N-glycans in RA increases with the disease progress, and returns to normal in the remission phase; both features were confirmed in the previous studies conducted in our laboratory .
Objectives The aim of this study was to evaluate agalactosylation factor (AF) in patients with PsA during biological treatment at Rheumatology Clinic, Medical University in Wroclaw. Patients were treated with adalimumab in combination with MTX, NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) or cyclosporine under permission of the Commission of Bioethics (Medical University, Wroclaw, Poland). The patients between 26-61 years old (mean 48) were diagnosed by the criteria recommended by CASPAR group.
Methods Immunoglobulin G was isolated from the serum samples using a column of Sephadex G-25 and DE52 anion exchange resin. The galactosylation of serum IgG was determined using an ELISA-plate test, with two lectins Ricinus communis (RCA-I) and Griffonia simplicifolia (GSL-II), separately. The IgG control was prepared from the pooled serum samples of 5 healthy persons. Triplet wells on a microplate were used for one sample. The ELISA- plate test was performed as previously described .
Results The relative binding of GSL –II and RCA –I was expressed as the absorbance given by tested sample, divided by the absorbance of the control sample; the ratio of relative GSL –II/RCA –I binding was termed as agalactosylation factor (AF) . We determined AF for IgG samples and a control sample. The AF of control was set to 1.0; we have previously  confirmed the AFs of IgG of healthy individuals are close to 1. The AF value for 5 patients decreased during therapy and this correlated with a concomitant decrease of initially elevated clinical parameters and with general improvement of patients’ health. The AF value of Bor was comparatively less elevated at the beginning of treatment and insensibly increased.
Conclusions The studies have shown higher AF in PsA patients compared to control (healthy people). During therapy with adalimumab decrease of AF was observed, which meant increase of galactosylation of IgG. We plan to perform tests on a larger group of patients.
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Pasek, M. et al., Galactosylation of IgG from rheumatoid arthritis (RA) patients – changes during therapy, Glycoconj. J., 23, 463-471, 2006;
Disclosure of Interest None Declared
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