[Presence of cryoprecipitates in the serum of patients with rheumatoid arthritis].

Serum samples from 140 controls (C) and from 72 patients suffering from defined rheumatoid polyarthritis (RP) were tested for cryoglobulins (CG). CG were found in 19.7 percent of C and 55 percent of RP : a highly significant difference (p less than or equal to 0.001). In the controls there was no correlation between the CG and age or sex. The RP with cryoglobulins seemed to have more inflammation, but systemic manifestations were not any more frequent than in the cryonegative RP. In the RP a correlation was noted between the presence of CG and the following parameters : increase in the sedimentation rate, rise in serum immunoglobulins, IgA and IgC, presence of antinuclear factors, and drop in the C4 fraction of complement. There was no correlation with the presence of the rheumatoid factor in the serum. In 33 cryoprecipitates in the RP, 7 contained IgG, 1 IgM, 22 IgM-IgG -- of which 11 contained C1q and 16 rheumatoid factor -- and 3 contained IgA-IgM-IgG -- of which 1 contained C1q and 2 rheumatoid factor. Some of the biochemical data support the hypothesis that likens these cryoglobulins to immune complexes.