American Society of Hematology

Figure 4.

$IgG fractions from COVID-19 patients in the ICU induce platelet apoptosis via crosslinking FcγRIIA. (A-C) Changes in apoptosis pathways induced by IgG fraction from COVID-19 patients in the ICU or COVID-19 patients not in the ICU, as well as non–COVID-19 patients in the ICU (control group) and healthy donors, were analyzed by assessing the depolarization of the ΔΨm (A), cytosolic calcium concentration (B), and PS externalization (C) in platelets from 3 different healthy donors. (D-F) The same assays were performed in the presence of the IV.3 monoclonal antibody (mAb) to block FcγRIIA signaling. Each dot represents 2 experiments with platelets from 2 different donors. Data are presented as mean ± SEM of the measured FI compared with control. Not significant, *P < .05, **P < .01, ***P < .001, ****P < .0001. The number of sera tested is reported in each graphic.$

IgG fractions from COVID-19 patients in the ICU induce platelet apoptosis via crosslinking FcγRIIA. (A-C) Changes in apoptosis pathways induced by IgG fraction from COVID-19 patients in the ICU or COVID-19 patients not in the ICU, as well as non–COVID-19 patients in the ICU (control group) and healthy donors, were analyzed by assessing the depolarization of the ΔΨm (A), cytosolic calcium concentration (B), and PS externalization (C) in platelets from 3 different healthy donors. (D-F) The same assays were performed in the presence of the IV.3 monoclonal antibody (mAb) to block FcγRIIA signaling. Each dot represents 2 experiments with platelets from 2 different donors. Data are presented as mean ± SEM of the measured FI compared with control. Not significant, *P < .05, **P < .01, ***P < .001, ****P < .0001. The number of sera tested is reported in each graphic.

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