Hepatitis C Virus and Cryoglobulinemia

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Abstract
Agnello et al. (Nov. 19 issue)1 report the detection of hepatitis C virus (HCV) RNA in serum samples from 16 of 19 patients with type II cryoglobulinemia. Using three different assays, they demonstrated antibodies to HCV in the samples from only 8 of the 16 patients positive for HCV RNA and in one of four cryoprecipitates from the patients positive for antibodies to HCV. These findings are surprisingly different from those obtained by several investigators using quite similar assays2-4. In our series of 51 patients with essential mixed cryoglobulinemia4 and in 24 additional patients subsequently studied, we found antibodies to HCV in serum from 19 of 51 patients (37 percent) with a first-generation enzyme-linked immunosorbent assay (ELISA), in 72 of 75 patients (96 percent) with a second-generation ELISA, and in 48 of 75 patients (64 percent) with a recombinant immunoblot assay. The prevalence of antibodies to HCV in the cryoprecipitates, after rheumatoid factor was eliminated by the use of dithiothreitol, was 94 percent and 96 percent with a first-generation ELISA and a second-generation ELISA, respectively. The extremely high prevalence of HCV antibodies detected by the second-generation ELISA in both serum samples and cryoprecipitates was the result of the invariable presence in these patients of antibodies to the structural c22-3 HCV antigen. We found HCV RNA in serum samples from 26 of 28 unselected patients with essential mixed cryoglobulinemia. However, in contrast to the results reported by Agnello et al., only 1 of these 26 HCV RNA-positive patients had serum and cryoprecipitate negative for HCV antibodies.