Figure 2. Anti-PEG antibody levels and COVID-19 mRNA vaccine-mediated hemolytic activity.

(A) Concentration of anti-PEG-IgE in serum of non-allergic (n=13, blue) and allergic individuals (n=19, orange) from the earliest timepoint of blood collection shortly after receiving the first dose of vaccine (Median: 11.5 days, Range 0 – 86 days). (B) Dot plot depicting concentration of anti-PEG-IgG in serum of non-allergic (n=13, blue) and allergic individuals (n=19), split into high (n=8, green) and low (n=11, pink) basophil responses, as characterized in Fig. 1. (C) Dot plot depicting concentration of anti-PEG-IgM in serum of non-allergic (n=13, blue) and allergic individuals (n=19), split into high (n=8, green) and low (n=11, pink) basophil responses, as characterized in Fig. 1. Values were compared between the two groups at the same relative times using two-tailed Mann-Whitney test. (D) Serum was incubated with BNT162b2 vaccine for 30 min to trigger complement activation. Residual complement activity in the serum following incubation with BNT162b2 vaccine is expressed as average residual hemolytic activity (Avg RHA). Dot plots showing Avg RHA in non-allergic (n = 13, blue) and allergic individuals (n = 19), split into high (n=8, green) and low (n=11, pink) basophil responses, as characterized in Fig. 1. Values were compared between the two groups at the same relative times using two-tailed Mann-Whitney test. (E) A subgroup of sera from allergic individuals were depleted of IgG (Dpl) and subjected to the hemolysis assay. Depletion was confirmed by the absence of IgG heavy and light chains by Western blotting (data not shown). Antibody depletion diminished complement activation, resulting in higher average RHAs in the majority of sera tested. Wilcoxon signed rank test, * P<0.05.