Search

Summary Background: Some properties of blood are modified post mortem. These modifications might give false-negative or false-positive results in infectious disease testing. Most CE-marked test equipment for infectious serology testing is not validated for testing post-mortal blood. Validation, however, is obligatory, if the results are used for the release of tissues for transplantation. Methods: Samples of pre- and post-mortem sera were obtained from 20 cornea donors, and the results were compared for anti-HIV-1/2, anti-HCV, HBsAg, and anti-HBc on the Siemens-BEP-III Automatic System. Negative post-mortem sera were spiked with standard sera (PEI anti-HCV IgG, PEI HBsAg ad 1000 standard, anti-HBc IgG (WHO) NIBSC 95/522, PEI anti-HIVIV) in concentrations which give low- and high-positive results for the respective marker. Results: All pre-mortem sera were negative for all markers. None of the post-mortem samples was false-positive. None of the spiked postmortem samples was false-negative. Technical errors occurred during the validation process but could be detected and eliminated. Serum samples should be centrifuged immediately after collection, and it must be taken into account that post-mortem serum could rarely lead to blockage of pipetting systems due to clotting phenomena. Conclusion: There is no indication that post-mortem samples give false-negative or false-positve results with the test system and test kits used. The procedure described might serve as a model for validating other test kits on post-mortem samples.

The German National Advisory Committee ‘Blood’ (Arbeitskreis Blut), recently recommended testing of blood and plasma donations for antibodies against the hepatitis B core antigen (anti-HBc). We assessed possible effects of this intended measure on donor deferral rate and look back procedures. Study Design and Methods: 3,964 consecutive blood donors were tested for anti-HBc for the first time. Anti-HBc-positive samples were further investigated employing an alternative anti-HBc test, quantitative determination of anti-HBs and HBV nucleic acid testing. Results: 46 (1.16%) of the samples were tested specifically anti-HBc-positive. Following the recommendations of the Arbeitskreis Blut, 9 (0.23% of all) donors had to be permanently deferred. Eight of these were repeat donors and had already donated 353 blood components which had been transfused to 285 recipients during the past 17 years. Conclusions: Implementation of anti-HBc testing in Germany will result in an acceptable loss of blood donors. However, the realization of look-back procedures is problematic due to the huge number of transfused blood components, the long period of time those donors gave blood, and particularly the impossibility to precisely determine the time of seroconversion. Therefore, when introducing anti-HBc testing, regulatory authorities should consider the described implications for look-back procedures.

The new automated Enzymun-Test® Anti-HBc Plus for the detection of antibodies to hepatitis B virus (HBV) core antigen (anti-HBc) after pretreatment with reducing agents dithiothreitol (25°C; + DTT) or potassium bisulfite (37°C; + MBS) was evaluated by testing 571 serum and plasma samples. The panel included dilution series of reference standards and samples from chronic carriers, one seroconversion panel, samples from patients in acute or chronic stage of the disease or resolved hepatitis B, preselected sera from blood donors that were initially reactive in an anti-HBc assay without pretreatment, potentially cross-reactive serum samples obtained from patients suffering from other diseases or with passed infections other than HBV, pregnant women and individuals with HBV vaccination. The IMx CORETM (Abbott Diagnostics) served as reference assay. Discrepant samples were further investigated with two different commercial anti-HBc enzyme immunoassays, other HBV-specific serological markers and HBV DNA hybridization. The sensitivity of the Enzymun-Test Anti-HBc Plus (25°C; + DTT, and 37°C; + MBS) in comparison to the reference assay was 100%. The IMx CORE showed a twofold higher sensitivity than Enzymun-Test Anti-HBc Plus for anti-HBc detection in dilution series of serum samples from HBV carriers. The agreement in terms of specificity of the Enzymun-Test Anti-HBc Plus (25°C; + DTT, and 37°C; + MBS) and in comparison to IMx CORE was 97.4 and 96.4%, respectively. After resolution of discrepant results (3 samples were tested false negative with IMx CORE), the agreement in terms of specificity of the Enzymun-Test Anti-HBc Plus (25°C; + DTT, and 37°C; + MBS) in comparison to the combination of the comparative assays was 98.3 and 97.4%, respectively. In conclusion, the new automated Enzymun-Test Anti-HBc Plus with sample pretreatment with DTT (25°C; + DTT) or MBS (37°C; + MBS) permits a highly sensitive and specific detection of anti-HBc in diagnostic virology and blood donation testing.

Sera of 85 asymptomatic HBsAg carriers found among blood donors were tested for anti-HBc titers and were retested 4 years later. The results were correlated with the histological findings of first and final biopsy. None of 75 HBsAg carriers with normal or minimally changed liver tissue, 71 of them anti-HBe positive, developed chronic inflammatory liver disease. 4 HBsAg carriers eliminated HBsAg from the serum after a 1-to 3-year HBsAg-carrier state and 2 developed antibody against HBsAg in the sequel. In 65 of 75 cases we found unchanged anti-HBc titers. The geometrical mean titer (GMT) was 1:7,800 in the first and 1:7,000 in the final examination with a range of 1:400 and 1:25,600 in the group of HBsAg carriers with normal liver, and was 1:14,200 and 1:10,300, respectively, with a range of 1:800 and 1:51,200 in HBsAg carriers with minimal changes. In both groups the decrease of anti-HBc concentration within 4 years was not significant. The group of 10 HBsAg carriers with chronic hepatitis did not differ from healthy HBsAg carriers in respect to anti-HBc titers. Anti-HBc titers varied between 1:6,400 and 1:25,600, the GMT was 1:13,700 and 1:12,800, respectively. It is speculated that in healthy HBsAg carriers shedding of serologically undetectable quantities of complete and/or defective HBcAg from liver cell nuclei which contain HBcAg not detectable by immunofluorescence maintain the production of anti-HBc.