Comparison of Four-Assay Systems for the Quantification of Hepatitis B Surface Antibody

Whang, Dong Hee; Shin, Bo Moon

Abstract

BACKGROUND: The hepatitis B surface antibody (anti - HBs) level has been used as an indicator for protective immunity after vaccination. Various kinds of assay systems including EIA (Enzyme Immunoas-say) and MEIA (Microparticle enzyme immunoassay) have been used for the quantification of that antibody. Although most anti - HBs assay systems have been standardized based on the WHO reference preparations, and results of the assay systems are in good agreement for most of the serums that were examined, some discrepancies in the cases have been observed among the various assay systems. In this study, four kinds of anti - HBs assay systems were compared for relative qualitative and quantitative results based on mIU/mL unit.
METHODS
Serum samples from five hundred visitors to the Health Care Center, Seoul Paik Hospital were assayed by Cobas Core Anti-HBs Quant EIA II (Roche), Enzygost Anti-HBs II (DADE Behring), AxSYM AUSAB (Abbott) and Elecsys Anti-HBs (Roche).
RESULTS
The concordance rates among the 4 assay kits were 92.8% (464/500) and 75.6% (378/500) was positive (anti - HBs > or =10 mIU/mL) and 17.2% (86/500) were negative. Among 36 samples (7.2%) showing discrepant results, 23 samples (4.6%) were negative by AxSym or Behring or both and positive by Elecsys or Cobas Core or both. Most of the discrepant samples showed low-level reactive results in the range of 10 to 100 IU/L for the other assay kits, which showed positive results. Quantitative agreements between 2 assay systems gave linear correlation coefficients ranging from
CONCLUSIONS
The quantification of anti - HBs can show various results according to the kind of assay kit used. Samples showing relatively low reactive results in the range of 10 to 100 mIU/mL when tested by Elecsys or Cobas Core should be especially interpreted cautiously because those same samples might be negative when tested by Behring or AxSYM.