Fig 1.
Correlative analysis of anti-SARS-CoV-2 serology tests and neutralization titer.
Ortho-Vitros platform assay was performed to detect total Immunoglobulin (Ig) against SARS-CoV-2 spike protein and expressed as signal to cut-off ratio (S/CO). Abbott platform assay was performed to detect gamma Ig (IgG) against SARS-CoV-2 nucleoprotein and expressed as Index value. (A) IC50 and S/CO values for total Ig against spike protein of matched samples were analyzed for correlation. (B) IC50 and Index values for IgG against nucleoprotein were analyzed for correlation. Spearman’s Correlation coefficient, ρ was determined in each scenario.
Table 1.
General characteristics and immune response parameters of 87 CCP donors.
Table 2.
Clinical demographics and hospital course for patients transfused CCP.
Table 3.
COVID-19 convalescent plasma transfusion details.
Fig 2.
COVID-19 outcome-based comparison of antibody responses in plasma recipients.
Mean values of neutralization IC50 (A), anti-spike total Ig S/CO values (B), and anti-nucleoprotein IgG index values (C) of transfused units were compared among plasma recipients at the extremes of COVID-19 outcomes (N = 7), death in hospital or discharge without oxygen requirement (N = 18). p-values were compared using Mann-Whitney tests.
Fig 3.
Variation in IC50 dependent on Fc receptor expression.
Variation in half-maximal inhibitory concentrations (IC50) between three stable cell lines (293T-ACE2, 293T-ACE2-FcαR, and 293T-ACE2-FcγRIIA) infected with an MLV viral particle pseudotyped with SARS-CoV-2 S protein and titrated with SARS-CoV-2 plasma or serum from convalescent donors. The variation in IC50 values was analyzed using a Kruskal-Wallis test, with horizontal lines representing median values.
Fig 4.
Correlations of anti-S titers with IC50 in cell lines expressing ACE2 and Fc receptors.
Neutralization titers of SARS-CoV-2 convalescent plasma or serum remain constant when titrated against cells with different Fc receptors. Differences between AUC of IgG, IgA, and IgM was analyzed using the Kruskal-Wallis test with horizontal lines representing median values (A). Half-maximal neutralizing titers (IC50) were compared against antibody titers calculated as area under the curve (AUC) from an anti-S ELISA that specifically quantifies anti-S IgG, IgA, or IgM antibodies. Correlation analysis of IgG (B,E,H), IgA (C,F,I), and IgM (D,G,J) ELISA AUC data vs. neutralization IC50 values for three stable cell lines expressing the human receptor ACE2 alone or in combination with FcαR or FcγRII, as indicated. Spearman correlation (ρ) values and absolute p-values (p) are indicated.