Gravity-driven crossflow membrane filtration and mechanical centrifugation yield plasma with equivalent total and COVID-19-specific immunoglobulin content

While the administration of convalescent plasma is a promising therapy for coronavirus disease 2019 (COVID-19), upfront costs and technological barriers of conventional plasmapheresis have limited the collection and processing of COVID-19 convalescent plasma (CCP) in Low- and Middle-Income Countries (LMICs). We previously reported that bedside plasma separation using gravity-driven microfiltration has made CCP therapy accessible as a treatment option in Suriname. However, the question remains whether the gravity-driven microfiltration method yields similar amounts of immunoglobulins as compared to conventional plasmapheresis. Here, we compared the gravity-driven microfiltration method with conventional plasma centrifugation for the total and COVID-19-specific immunoglobulin content of the obtained CCP. Blood donations from 10 donors recovered from PCR-confirmed COVID-19 were processed using both methods. Samples were collected pre- and post-processing for analysis to allow direct comparison of both methods. There were no differences in COVID-19-specific IgG levels between convalescent plasma obtained by microfiltration and centrifugation for 4 of the 5 assays used. Anti-RBD-Omicron IgG levels were slightly higher in the plasma obtained after filtration (median 274, range 69 to 1258) than after centrifugation (median 249, range 67 to 1175), Wilcoxon P = 0.0488. No significant differences were detected between the two methods for levels of total albumin, total cholesterol, total IgA, IgM and IgG levels. These results indicate that gravity-driven microfiltration and conventional centrifugation yield CCP with equivalent amounts of total and COVID-19-specific antibodies. This makes the gravity-driven microfiltration method a viable option for the collection and treatment with CCP in the LMICs setting.