OCCURRENCE OF DEFICIENT GALACTOSYLATION OF SERUM IGG PRIOR TO THE ONSET OF RHEUMATOID-ARTHRITIS

Previous reports have shown that deficient galactosylation of serum Ig G occurs in patients with rheumatoid arthritis (RA) and other autoimmu ne disorders. In this study, we investigated the relationship between galactosylation of serum IgG and disease status in a population of Pim a and Papago Indians, who are characterized by a frequent occurrence o f RA. The mean galactose levels of serum IgG collected from 11 individ uals 1.5-10 years prior to onset (T1), at onset (T2), and 1.7-7 years post-onset (T3) of RA were lower than those from 25 seronegative contr ols without RA from the same population (P=0.01, 0.005, and less than or equal to 0.001, respectively). The mean galactose content of IgG de creased in the order T1>T2>T3, but the differences were not significan t. The galactosylation of serum IgG from the RA patients did not diffe r from that of seropositive Pima Indian controls who did not develop R A over the course of study. The occurrence of IgG galactose deficiency in individuals with RA prior to the onset of the disease supports the contention that this phenomenon may be a risk factor for the developm ent of RA. Furthermore, the occurrence of IgG galactose deficiency in healthy seropositive individuals suggests a relationship between dimin ished galactosylation and induction of rheumatoid factor (RF).