Cryoglobulins in cases of rheumatoid arthritis.

Clinically diagnosed cases with different grades of rheumatoid arthritis (RA) were studied for (a) cryoglobulin content (b) constituents of cryoglobulins, and (c) rheumatoid factor (RF) titers in sera and cryoglobulins. Of 60 patients, 28 (46.66%) had significantly high levels of cryoglobulins and were mainly distributed in the severe group. Significant amounts of IgG and IgM were found in the cryoglobulins of the 15 cases of RA studied. Ten of these cases had detectable C3 in their cryoglobulins. Of 20 cases of RA, 10 had detectable levels of RF in their cryoglobulins, as shown by the latex agglutination method. There was no significant correlation between the RF titers of cryoglobulins and the RF titers in the corresponding sera or the quantity of IgM and IgG components in them. Since the RF titer in cryoglobulin seemed to indicate the severity of the disease, the use of this parameter is proposed for diagnosis and prognosis of RA.