Immunoadsorption as a method of antibody donation during the COVID‐19 pandemic

Abstract

AbstractBackground and ObjectivesInitial therapeutic efforts to treat severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) included the use of plasma from convalescent donors containing anti‐SARS‐CoV‐2 antibodies. High‐neutralizing antibody titres are required for therapeutic efficacy. This study aims to show that immunoadsorption followed by tangential flow filtration can be used to obtain antibody concentrates with high‐neutralizing capacities.Materials and MethodsEligible donors (n = 10, five males and three females) underwent immunoadsorption using adsorber columns specific for human antibodies. Glycine‐washed out eluates of 1.5 L volume were further concentrated by tangential flow filtration using 30 kDa ultrafiltration membranes. The same membranes were applied for diafiltrations to exchange residual glycine for 0.9% normal saline.ResultsAntibody concentrates were obtained within 8 h from the start of donation and had 4.58 ± 1.95, 3.28 ± 1.28 and 2.02 ± 0.92 times higher total IgG, IgA and IgM concentrations, 3.29 ± 1.62 and 3.74 ± 0.6 times higher SARS‐CoV‐2 N and S antibody concentrations and 3.85 ± 1.71 times higher SARS‐CoV‐2 S‐specific IgG concentrations compared to the donors' peripheral blood. The specific SARS‐CoV‐2 virus neutralization capacities increased in all but one concentrate. All antibody concentrates (50–70 mL final volume) passed microbiological tests, were free of hazardous glycine levels and could be stored at −80°C and 4°C for 1 year with 20 ± 3% antibody loss.ConclusionImmunoadsorption followed by tangential flow filtration is a feasible procedure to collect IgG, IgA and IgM as well as SARS‐CoV‐2 N‐ and S‐specific antibody concentrates of low volume, free of albumin and coagulation factors. Whether these concentrates can be used as passive immunisation in infected patients remains to be elucidated.