Background

In the fight against the Covid-19 Pandemic, administration of plasma from convalescent donors containing anti-SARS-CoV-2 antibodies, though promising according to case reports, failed to show a clear benefit in a greater number of trials. We hypothesize that instead of collecting whole plasma units, convalescent donors could donate solely immunoglobulins by undergoing immunoadsorption, a mode of therapy regularly applied in autoimmune diseases.

Methods

Immunoadsorption using an affinity column adsorber pair (TheraSorb, Miltenyi Biotech) was performed on 6 convalescent plasma donors (4 male and 2 female) that had been tested positive for COVID-19 prior to antibody donations. The resulting eluate contained IgG, IgA and IgM dissolved in a glycine buffer. For bioburden reduction, a Tangential Flow Filtration System (Centramate LV, Pall Corporation) was used to concentrate the eluate and exchange glycine for 0.9% NaCl using diafiltration. The final antibody concentrate was finally sterile filtered, before storage at 4°C or freezing at -80°C.

Results

Immunoadsorptions were very well tolerated with no side effects. Collected and neutralized eluates were concentrated using Tangential Flow Filtration. The concentrates contained three times more IgG, IgA and IgM as well as specific SARS-CoV2 N and S antibodies compared to the peripheral blood of the donors. The specific SARS-CoV2 virus neutralization capacity was not diminished but rather increased in all but one donation. All ACs passed sterility tests at the collection day and could be stored at -80°C and 4°C with minor loss of function.

Conclusion

Immunoadsorption proved to be a feasible method of antibody donations for the collection of IgG, IgA and IgM as well as SARS-CoV2 N and S specific antibodies. The antibody concentrates could be produced within one day and final antibody neutralization titers in the ACs were found to be comparatively high. All ACs were sterile, free of hazardous glycine levels and could possibly be administered as a potential therapeutic approach.

Offenlegung Interessenkonflikt:

Jannik Rothenburg is employed by PALL Corporation

Silke Rink-Baron is an employee of Miltenyi Biotec.

Lisa Mueller, Philipp Niklas Ostermann, Johannes C. Fischer, Derek Hermsen, Johannes Stegbauer and Anja Moldenhauer have nothing to disclose.