Hepatitis C Virus and Intravenous Immune Globulin-Reply

In Reply. —We, like Dr Macy, did not expect the high rate of detection of anti-HCV in this cohort of immunodeficient patients. In prior reports of HCV transmission to patients with primary hypogammaglobulinemia following IGIV administration, 2% to 27% of patients with HCV RNA detected by reverse transcriptase—polymerase chain reaction had detectable anti-HCV. 1,2 Variability in the proportion of immunodeficient patients with detectable anti-HCV may reflect differences in the patient population, differences in the timing of anti-HCV testing, or both. We are not aware of any unique features of HCV or the recombinant HCV antigens in the antibody test that would account for immunodeficient patients responding at a higher rate to these antigens than to other viral antigens. We agree with Dr Mosley that further laboratory studies are needed to determine the exact reasons for the infectivity of Gammagard. However, there was no evidence that changes in either plasma donor sources or