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K. Althaus et al.
AB
Figure 3. Binding profile of sera from vaccine-induced immune thrombotic thrombocytopenia. (A) Results of the PF4/heparin immunoglobulin G (IgG)-enzyme immune assay (EIA) in patients with vaccine-induced immune thrombotic thrombocytopenia (VITT) with and without 100 IU/mL heparin. All VITT patients showed an enhanced binding which was significantly inhibited at high dose of heparin (100 IU/mL). (B) PF4-seroconversion after vaccination and severe SARS-CoV2 infection was followed up. IgG PF4/heparin antibody binding results in healthy volunteers before and after vaccination and COVID-19 patients in intensive care units showed four vaccinated volunteers displaying a positive EIA result after 7-14 days post-vaccination (red empty diamonds). OD: optical density.
Figure 4. Immunoglobulin G bind- ing to platelets by flow cytometry in sera of vaccine-induced immune thrombotic thrombocy- topenia patients. Immunoglobulin G (IgG) binding to healthy washed platelets (PLT) after incubation with sera from vaccine-induced immune thrombotic thrombocytopenia (VITT) patients was measured (assessed by flow cytometry and expressed as fold increase (FI) nor- malized to controls). VITT patients showed significantly higher binding at the baseline in comparison to healthy controls, which was inhibit- ed by high dose heparin. ns: not significant; *P<0.05, **P<0.01, ***P<0.001 and ****P<0.0001.
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haematologica | 2021; 106(8)