Anti-SARS-Cov-2 S-RBD IgG Formed after BNT162b2 Vaccination Can Bind C1q and Activate Complement

Figure 2

Measurement of C1q and MBL binding and their correlation to immunoglobulins. Participants were divided by their vaccination status, type of vaccine, and dose of vaccine. Serum samples were incubated with RBD-coated plates; bound C1q was subsequently measured using an indirect sandwich immunoassay. (S/N) represents the chemiluminescence signal generated from wells incubated with 1% serum divided by the signal in control wells incubated with PBST. (a) Represents bound C1q levels while (b) represents bound MBL levels. (c) A log-log scatter plot that correlates C1q to anti-RBD IgG and (d) a log-log scatter plot that correlates C1q to anti-RBD IgA levels in all vaccinated participants. (e) and (f) are scatter plots that correlate MBL to anti-RBD IgG and IgA levels, respectively, in all vaccinated participants. Spearman’s correlation coefficient (r_s), value, and the number of participants () are displayed on the plot. (g) Individual values of C1q (S/N) per anti-RBD IgG (S/N) in each participant were calculated and displayed in a scatter plot for the two types of vaccines. In scatter plots, each circle represents one participant, bold horizontal lines represent the mean of each group, while whiskers represent the standard deviation. Dunn’s multiple comparisons statistical test following Kruskal–Wallis test was used to compare various groups to the unvaccinated group. Only significant pairwise comparisons are displayed, , .

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