AUTHOR=Ravlić Sanda , Hećimović Ana , Kurtović Tihana , Ivančić Jelečki Jelena , Forčić Dubravko , Slović Anamarija , Kurolt Ivan Christian , Mačak Šafranko Željka , Mušlin Tatjana , Rnjak Dina , Jakšić Ozren , Sorić Ena , Džepina Gorana , Đaković Rode Oktavija , Kujavec Šljivac Kristina , Vuk Tomislav , Jukić Irena , Markotić Alemka , Halassy Beata TITLE=Is Better Standardization of Therapeutic Antibody Quality in Emerging Diseases Epidemics Possible? JOURNAL=Frontiers in Immunology VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.816159 DOI=10.3389/fimmu.2022.816159 ISSN=1664-3224 ABSTRACT=

During the ongoing COVID-19 epidemic many efforts have gone into the investigation of the SARS-CoV-2–specific antibodies as possible therapeutics. Currently, conclusions cannot be drawn due to the lack of standardization in antibody assessments. Here we describe an approach of establishing antibody characterisation in emergent times which would, if followed, enable comparison of results from different studies. The key component is a reliable and reproducible assay of wild-type SARS-CoV-2 neutralisation based on a banking system of its biological components - a challenge virus, cells and an anti-SARS-CoV-2 antibody in-house standard, calibrated to the First WHO International Standard immediately upon its availability. Consequently, all collected serological data were retrospectively expressed in an internationally comparable way. The neutralising antibodies (NAbs) among convalescents ranged from 4 to 2869 IU mL-1 in a significant positive correlation to the disease severity. Their decline in convalescents was on average 1.4-fold in a one-month period. Heat-inactivation resulted in 2.3-fold decrease of NAb titres in comparison to the native sera, implying significant complement activating properties of SARS-CoV-2 specific antibodies. The monitoring of NAb titres in the sera of immunocompromised COVID-19 patients that lacked their own antibodies evidenced the successful transfusion of antibodies by the COVID-19 convalescent plasma units with NAb titres of 35 IU mL-1 or higher.