Does it take sugar? A clinical role for measuring the glycosylation of IgG?

Is IgG galactosylation the relevant factor for pregnancy-induced remission of rheumatoid arthritis?

During pregnancy, most patients with rheumatoid arthritis (RA) experience spontaneous improvement of their disease activity. Among the soluble candidates that have been investigated in search for the most relevant disease-remitting factor are the galactosylation levels of immunoglobulin G (IgG). In RA, a higher percentage of IgG lacking the terminal galactose residues, thought to play a pro-inflammatory role, is found. During pregnancy, however, IgG galactosylation levels increase and correlate with improved disease activity. The question remains whether the increase in IgG galactosylation during pregnancy is a mere epiphenomenon or a true remission-inducing factor.

Galactosylation of IgG from rheumatoid arthritis (RA) patients--changes during therapy

It is well documented that serum IgG from rheumatoid arthritis (RA) patients exhibits decreased galactosylation of its conservative N-glycans (Asn-297) in CH2 domains of the heavy chains; it has been shown that this agalactosylation is proportional to disease severity. In the present investigation we analyzed galactosylation of IgG derived from the patients using a modified ELISA-plate test, biosensor BIAcore and total sugar analysis (GC-MS). For ELISA and BIAcore the binding of IgG preparations, purified from the patients' sera, to two lectins: Ricinus communis (RCA-I) and Griffonia simplicifolia (GSL-II) was applied. Based on ELISA-plate test an agalactosylation factor (AF, a relative ratio of GSL-II/RCA-I binding) was calculated, which was proportional to actual disease severity. Repeated testing of several patients before and after treatment with methotrexate (MTX) alone or in combination with Remicade (a chimeric antibody anti-TNF-alpha) supplied results indicating an increase of IgG galactosylation during the treatment. This introductory observation suggests that IgG galactosylation may be an additional indicator of the RA patients' improvement.

Pregnancy and rheumatoid arthritis

Amelioration of rheumatoid arthritis (RA) occurs in about three quarters of pregnancies. Most women who improve experience initial relief in the first trimester. RA almost invariably recurs within 3 to 4 months of delivery. The effect of pregnancy upon the risk of first developing RA is similar in some respects but also differs from that observed in women with established disease. Analogous to women with established disease, the chance of a woman first developing RA is significantly reduced during pregnancy but increased in the first year post partum; thereafter risk is decreased. There is no indication of any adverse effects of RA on pregnancy outcome. Although limited, some medications can be used during pregnancy and during lactation without jeopardizing the well-being of the fetus.