Immunoglobulin (IgG and IgM) Metabolism in Patients with Rheumatoid Arthritis

Abstract

The immunoglobulin metabolism in rheumatoid arthritis was investigated by turnover studies with [¹²⁵I] IgG in 20 patients and simultaneously with [¹³¹I] IgM in 17 of the cases. In the vast majority the plasma concentrations of IgG and IgM were within the normal range. Mean values for the fractional catabolic and synthetic rates were significantly increased. Except for rates of synthesis, the metabolic variables of the two proteins were found not to be correlated. The turnover of IgG and IgM tended to increase with the activity of the disease as estimated by clinical examination, but no correlation was found between the turnover of either protein and any of the laboratory data.

Key Words:

• Fractional catabolic rate
• immunoglobulins
• plasma concentration
• radioiodination
• rate of synthesis
• rheumatoid arthritis
• turnover