Serum IgG galactosylation in psoriatic arthritis patients undergoing a biological treatment. A preliminary report

Abstract

Aim of the study : A group of psoriatic arthritis patients (PSA, 11 cases) has undergone a treatment. For each patient two serum samples were collected: before the treatment (sample before) and after the treatment (sample after). Performed investigation aimed to provide an information whether a treatment of the PSA patients improves the galactosylation of IgG N-glycans, which previously was shown for rheumatoid arthritis (RA) patients. Material and methods : Immunoglobulin G (IgG) was isolated from serum of PSA patients, before and after the treatment, using affinity chromatography on Protein A-Sepharose, and was further analyzed regarding the galactose content, using gas chromatography-mass spectrometry (GC-MS) method and ELISA test, performed with two lectins: Ricinus communis (RCA-I) and Griffonia simplicifolia (GSL-II). Based on ELISA results an agalactosylation factor (AF) was calculated for each before and after IgG sample. Results: Obtained data regarded galactose content in IgG, AF calculation and estimation of two laboratory indices of inflammation: erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) concentration in serum. Based on statistical methods it was shown that average difference (d) of after and before measures of AF for PSA patients was Med HL = –0.097 (95% CI: –0.49–0.25), which means that applied treatment did not affect AF value for this group of patients in a statistically significant manner (p = 0.2936). Conclusions: The study demonstrated that, in the contrary to RA patients, IgG galactosylation in PSA patients, undergoing a treatment, showed no statistically significant changes.

Keywords

• psoriatic arthritis
• immunoglobulin G
• IgG galactosylation
• N-glycans