{"title":"Conversion Factors to Compare Serum Concentrations of Anti-HBs, Anti-SARS-CoV-2 and Anti-Tetanus Toxin IgG.","authors":"Aurelia Knispel, Christian Jassoy","doi":"10.3390/antib14030069","DOIUrl":null,"url":null,"abstract":"<p><p><b>Background</b>: The concentration of antigen-specific antibodies in serum is usually measured in international units/mL. Therefore, the actual concentration of virus-specific antibodies in sera is unknown. <b>Objectives</b>: The aim of the study was to determine conversion factors for concentrations of IgG against hepatitis B surface antigen (HBs), SARS-CoV-2 receptor binding domain (RBD) and nucleoprotein (NP) as well as tetanus toxin (Ttx) in serum and to compare antigen-specific IgG concentrations in serum samples. <b>Methods</b>: Absorption equivalence ELISAs were used to determine conversion factors for international units (IU) for anti-HBs, anti-SARS-CoV-2-RBD and NP and for anti-Ttx immunoglobulin G. The antigen-specific IgG concentrations in serum samples were then measured in units/mL and the ratio of IgG concentrations in the sera was determined using the conversion factors. <b>Results</b>: One IU of anti-HBs IgG corresponded to 24.4 BAU of anti-CoV-2 RBD IgG, 6.87 BAU of anti-CoV-2 NP and 14 mIU of anti-Ttx IgG. One BAU anti-SARS-CoV-2 NP-specific IgG is equivalent to 3.5 BAU SARS-CoV-2 RBD-specific IgG. Conversion of international units showed that median serum anti-Ttx-IgG concentrations were 50 times higher and anti-CoV-2-RBD-IgG concentrations were 390 times higher than median anti-HBs-IgG concentrations. In addition, after SARS-CoV-2 infection, the concentration of NP-specific IgG in serum was generally higher than that of RBD-specific IgG. <b>Conclusions</b>: The study provides conversion factors for serum concentrations of IgG against HBs, SARS-CoV-2 RBD and NP, as well as Ttx-IgG. This offers new insights into serum IgG concentrations and allows conclusions to be drawn about plasma cell pools.</p>","PeriodicalId":8188,"journal":{"name":"Antibodies","volume":"14 3","pages":""},"PeriodicalIF":2.7000,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12371921/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Antibodies","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3390/antib14030069","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"IMMUNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background: The concentration of antigen-specific antibodies in serum is usually measured in international units/mL. Therefore, the actual concentration of virus-specific antibodies in sera is unknown. Objectives: The aim of the study was to determine conversion factors for concentrations of IgG against hepatitis B surface antigen (HBs), SARS-CoV-2 receptor binding domain (RBD) and nucleoprotein (NP) as well as tetanus toxin (Ttx) in serum and to compare antigen-specific IgG concentrations in serum samples. Methods: Absorption equivalence ELISAs were used to determine conversion factors for international units (IU) for anti-HBs, anti-SARS-CoV-2-RBD and NP and for anti-Ttx immunoglobulin G. The antigen-specific IgG concentrations in serum samples were then measured in units/mL and the ratio of IgG concentrations in the sera was determined using the conversion factors. Results: One IU of anti-HBs IgG corresponded to 24.4 BAU of anti-CoV-2 RBD IgG, 6.87 BAU of anti-CoV-2 NP and 14 mIU of anti-Ttx IgG. One BAU anti-SARS-CoV-2 NP-specific IgG is equivalent to 3.5 BAU SARS-CoV-2 RBD-specific IgG. Conversion of international units showed that median serum anti-Ttx-IgG concentrations were 50 times higher and anti-CoV-2-RBD-IgG concentrations were 390 times higher than median anti-HBs-IgG concentrations. In addition, after SARS-CoV-2 infection, the concentration of NP-specific IgG in serum was generally higher than that of RBD-specific IgG. Conclusions: The study provides conversion factors for serum concentrations of IgG against HBs, SARS-CoV-2 RBD and NP, as well as Ttx-IgG. This offers new insights into serum IgG concentrations and allows conclusions to be drawn about plasma cell pools.
期刊介绍：
Antibodies (ISSN 2073-4468), an international, peer-reviewed open access journal which provides an advanced forum for studies related to antibodies and antigens. It publishes reviews, research articles, communications and short notes. Our aim is to encourage scientists to publish their experimental and theoretical results in as much detail as possible. There is no restriction on the length of the papers. Full experimental and/or methodical details must be provided. Electronic files or software regarding the full details of the calculation and experimental procedure - if unable to be published in a normal way - can be deposited as supplementary material. This journal covers all topics related to antibodies and antigens, topics of interest include (but are not limited to): antibody-producing cells (including B cells), antibody structure and function, antibody-antigen interactions, Fc receptors, antibody manufacturing antibody engineering, antibody therapy, immunoassays, antibody diagnosis, tissue antigens, exogenous antigens, endogenous antigens, autoantigens, monoclonal antibodies, natural antibodies, humoral immune responses, immunoregulatory molecules.
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