[A benign form of rheumatoid arthritis, associated with low IgG, IgM and IgA and C3-proactivator concentrations in the serum].

In 31 case studies, 29 patients diagnosed with definite rheumatoid arthritis and 2 patients with probable rheumatoid arthritis were investigated. The duration of the disease averaged 8 years with 3 years being the minimum. These patients received either no basic therapy or had not been treated six months previous to the investigation. Patients with low levels of immunoglobulins were shown to have significantly better functional capacity (Steinbrocker) and significantly less synovitis, erosions and joint destructions despite longer duration of the disease than the control group with higher levels of immunoglobulins and C3-proactivator. All patients with this benign development of rheumatoid arthritis had an IgG-level below 1000 mg/100 ml (mean 767 mg/100 ml +/- 166) and low levels of IgA (mean 194 mg/100 ml +/- 73), IgM (mean 111 mg/100 ml +/- 53) and C3-proactivator (mean 23 mg/100 ml +/-6). 50% of these patients had positive rheumatoid factors.