Page 200 - Haematologica Vol. 107 - September 2022

ARTICLE - ITP antibody predicts desialylation and apoptosis S.S. Zheng et al.
desialylation, when compared to the controls, antibody positive patients’ sera disrupted mitochondrial ΔΨm more effectively than the antibody negative group (Figure 3B). Importantly, these changes are induced by the IgG fraction of ITP sera (Figure 3C). Therefore, the presence of APA in ITP sera induces platelet apoptosis as determined by changes in mitochondrial ΔΨm.
Anti-GPIIb/IIIa antiplatelet antibodies induce platelet apoptosis via Fcγ receptor
Prior literature demonstrated that the platelet desialylat- ing capacity of anti-GPIba antibody was FcγR-indepen- dent.28 However, in the case of anti-GPIIb/IIIa antibodies induced ITP, we and others have shown that FcγR is the driver of antibody-mediated platelet desialylation.36,37 Also
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Figure 2. Effect of immune thrombo- cytopenia patient sera on platelet de- sialylation and activation. (A and B) NEU1 surface translocation and (C and D), RCA- 1 lectin binding comparing patient sub- groups and controls. (E) Effect of purified immune thrombocytopenia (ITP) immu- noglobulin G (IgG) (50 μg/mL) on RCA-1 lectin binding. (F and G) P-selectin ex- pression on control and patient sera treated platelets. (H) P-selectin ex- pression on platelets treated with GPIIb/IIIa or GPIb/IX antibodies. CTRL: control; Pt: patient; Neg: antibody- negative; Pos: antibody-positive; MFI: mean fluorescence intensity. Data shown as mean ± standard deviation. Levels of significance are expressed as P-values. ns: non-significant, *P<0.05, **, P<0.01. Mann Whitney and Kruskal-Wallis test with Dunn’s multiple comparison.