Observations on Cryoglobulin Testing: I. The Association of Cryoglobulins Containing Rheumatoid Factors with Manifestation of Cryoglobulinemic Vasculitis

Objective. To investigate the results of mixed cryoglobulin tests performed on patients with and without hepatitis C virus (HCV) infection, to determine whether type II cryoglobulins containing rheumatoid factor (Type II-RF) were associated with cryoglobulinemic vasculitis. Methods. The cryoglobulin test protocol differed from the routine protocol. In addition to determination of both cryoglobulin concentration and immunoglobulin composition, the presence or absence of RF concentrated in the cryoglobulins was determined. Results. A qualitative and quantitative association of Type II-RF cryoglobulins with cryoglobulinemic vasculitis was present among HCV-infected patients. Conclusion. Detection and quantification of Type II-RF may enhance clinical monitoring of cryoglobulinemic vasculitis in HCV-infected patients. (First Release June 15 2009; J Rheumatol 2009; 36:1953-5; doi: 10.3899/jrheum.081035)