Evaluation of Potencies of Immune Globulin Products Against Hepatitis A

Passive immunization with human immune globulin (IG) is recommended for prophylaxis against hepatitis A and infection with its causative agent, hepatitis A virus (HAV). Immune globulin preparations administered intramuscularly (0.02 mL/kg) may confer protection for up to 3 months.¹ Because anti-HAV antibody levels are declining in plasma donors from developed countries,² we evaluated antibody levels in currently marketed IG products. Several products had lower-than-expected anti-HAV potencies, potentially conferring protection of reduced magnitude or duration against hepatitis A.

We evaluated 9 intramuscular IG preparations: 4 single lots manufactured in the Netherlands (GammaQuin, Sanquin), Germany (Beriglobin, CSL Behring), the United Kingdom (Subgam, Blood Products Laboratory), and Korea (Gamma-globulin, Green Cross); and 5 lots manufactured in the United States (GamaSTAN S/D, Grifols), termed Gamastan-1 to -5. Anti-HAV IgG and neutralizing potencies were determined against the Second World Health Organization International Standard for Anti-Hepatitis A Human Immunoglobulin. The content of anti-HAV IgG and neutralizing antibodies was measured by an immunoassay (ARCHITECT HAVAB-IgG, Abbott Diagnostics) and an end point dilution antibiotic resistance titration assay (ARTA) based on infection with an HAV construct containing a blasticidin resistance gene.³ Potencies were compared using the Tukey test (2 sided), with α set at .05. Daily decay of plasma anti-HAV antibodies was modeled^4(pp28-38) assuming a best-case scenario of complete absorption of 0.02 mL/kg of IG¹ following intramuscular delivery, distribution volume equal to twice the plasma volume, and maximal attainment of plasma concentrations 8 days after administration.⁵

Because commercial IG preparations were derived from plasma pools, the identity of human subjects cannot be ascertained by the investigators and there was no requirement for institutional review board review.

The anti-HAV IgG potency of GammaQuin was significantly higher than that of all the other preparations, followed by Beriglobin. Gamma-globulin, Subgam, and all the GamaSTAN S/D lots were not significantly different from each other (Figure, A). The anti-HAV neutralizing potency of GammaQuin was significantly higher than that of the other 8 preparations (Figure, B). Correlation between immunoassay- and ARTA-derived potencies was high (Pearson coefficient, 0.95; P = .002).

Modeling of anti-HAV IgG decay in plasma after IG inoculation⁵ showed that postabsorption anti-HAV IgG levels greater than 10 mIU/mL, deemed protective against infection,² were maintained by Subgam and Gammastan-4 for 1 day and for Gamastan-5, Beriglobin, and GammaQuin for 19, 40, and 53 days, respectively, whereas none of the other 4 preparations tested reached potentially protective levels (Figure, C). Beriglobin and GammaQuin were the only 2 IG preparations that reached anti-HAV neutralizing antibody levels greater than 10 mIU/mL, which were maintained for 18 and 35 days after absorption, respectively (Figure, D).

Currently, intramuscular IG is used for preexposure and postexposure prophylaxis against HAV infection.¹ Our data show that IG manufactured from plasma donors with declining herd immunity to HAV yielded low anti-HAV IG potencies. Only 2 of the 9 IG preparations tested had anti-HAV IgG potency greater than 100 IU/mL, which is the minimal potency stipulated by the European Pharmacopoeia for intramuscular IG preparations intended for hepatitis A prophylaxis.^6(p769) Our modeling shows that GammaQuin, Beriglobin, Subgam, and only 2 GamaSTAN S/D lots (Gamastan-4 and -5) achieved protective levels of anti-HAV IgG, but the duration of protection falls short of the expected 3 months. Similar levels of anti-HAV antibodies in plasma were estimated using a model validated for anti-HAV antibodies² (data not shown). Approaches to improve anti-HAV protection by IG potentially include increasing the dosage or producing lots from plasma of hyperimmunized donors.² In the United States, Grifols has informed the Food and Drug Administration that it is in the process of establishing a higher-dosage regimen and considering using plasma from donors with elevated HAV antibody levels to increase titers in GamaSTAN S/D.

Anti-HAV potencies determined by immunoassay or ARTA were not identical but showed high correlation. Variance is attributable to the assays measuring different antibody spectra, and immunoassay-detectable antibodies not being entirely neutralizing. Adopting a functional HAV neutralization assay such as ARTA³ would be appropriate for future evaluation of postimmunization protection and product efficacy.

Corresponding Author: Alexandra Tejada-Strop, MS, Centers for Disease Control and Prevention, Division of Viral Hepatitis, 1600 Clifton Rd NE, Mailstop A33, Atlanta, GA 30329 (atejadastrop@cdc.gov).

Correction: This article was corrected on February 6, 2017, to fix an omitted author contribution.

Published Online: January 9, 2017. doi:10.1001/jamainternmed.2016.9057

Author Contributions: Ms Tejada-Strop and Dr Costafreda had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Ms Tejada-Strop and Dr Costafreda served as co–first authors, each with equal contribution to the manuscript.

Concept and design: Costafreda, Kaplan, Teo.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: All authors.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Tejada-Strop, Costafreda, Dimitrova.

Obtained funding: Kaplan.

Administrative, technical, or material support: Kaplan, Teo.

Supervision: Costafreda, Kaplan, Teo.

Conflict of Interest Disclosures: None reported.

Funding/Support: This study was supported by US Food and Drug Administration (FDA) intramural funds to Dr Kaplan; also, the appointment to the Research Participation Program at the Center for Biologics Evaluation and Research (CBER) administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the US Department of Energy with the Centers for Disease Control and Prevention (Ms Tejada-Strop) and the FDA (Dr Costafreda).

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention or the US Food and Drug Administration.

Additional Contributions: We thank Y. Choi, PhD, for facilitating procurement of IG products, and M. Kodani, PhD, for guidance from the Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, Georgia. There was no compensation for their contributions.