Serum levels of IgA, IgG and IgM were measured in 46 patients (34 women, 12 men) with rheumatoid arthritis. The duration of the disease ranged from 6 months to 30 years; the patients follow-up ranged from 6 months to 12 years.
Serum IgA levels higher than the normal (> 450 mg/dl) were found in 20 patients (43.4%). These patients had mean levels of IgG, C3c and erythrocyte sedimentation rate significantly higher than the patients with normal IgA levels.
A significant relationship between the IgA levels and the activity of the disease or its clinical and radiological features was not observed. On the other hand, a relationship was observed between IgA levels and the mean duration of the disease which was significantly more prolonged in patients with high IgA serum levels.