Immunoadsorption as a method of antibody donation during the Covid-19 pandemic

ABSTRACT

Background: Treatments are being developed against severe Covid-19 symptoms, among them the use of convalescent plasma. Two drawbacks are, the large volumes of plasma needed for treatment can lead to circulatory overload, and the plasma contains unnecessary components that can lead to unwanted side-effects. We investigated the use of immunoadsorption followed by tangential flow filtration as a method to obtain highly concentrated Covid-19 antibody concentrates free of additional plasma components. Method(s) Five convalescent plasma donors (3 men and 2 women) have participated in this study. Two donors donated twice with 1 year gap between the donations. Immunoadsorption was performed with an affinity column adsorber pair (Miltenyi Biotec, Bergisch-Gladbach, Germany). The resulting eluate contained antibodies dissolved in a glycine buffer with a total volume of 1100- 1500mL. Tangential Flow Filtration System was used to concentrate all eluates 15- 21.3-fold using an Omega 30 kD membrane (Pall Corp, Dreieich, Germany) and to exchange the glycine buffer with 0.9% NaCl. Eluates were then filtered through a sterile filter, before storage at 4degreeC and -80degreeC. Result(s) All donors have tolerated the immunoadsorption very well with no side effects. The final product contained between 5mg and 194mg of CoV-2 antibodies per donation at a median end-volume of 61+/-20ml leading to probably eight times more COVID-19 antibodies than in one plasma unit while preserving or even increasing their neutralization capacity up to ten-fold. Glycine levels were reduced to non-hazardous 12.6+/-20 mumol (see table 1). The product was sterile and remained stable for 0.5 to 1 year in storage. In two cases the concentration of SARS-COV2 antibodies even increased during storage. Conclusion(s) Immunoadsorption followed by tangential flow filtration produces CoV2 antibody concentrates of high concentrations without simultaneous removal of unnecessary plasma components. The procedure can be done within one day, including the donation, without compromising the donor's immune system. Whether these donated antibodies can be used as passive immunization in acutely infected patients remains to be elucidated. (Table Presented).