PMC6439352_01
Patient's evolution under specific ITP treatments: platelet count (red line) as a function of days since ITP diagnosis and treatments administered (arrows), especially steroids (blue line), and eltrombopag (green line). *Intermittent bleeding was successive gastrointestinal hemorrhages, initially with and then without acute anemia, localized petechial or ecchymotic purpura and spontaneous hemorrhagic oral bullae. IVIGs, intravenous immunoglobulins.
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F1
According to the international consensus and after those therapeutic failures (Figure 1), refractory ITP was diagnosed.
Proteomic and immunohistochemistry analyses on patient's platelets and tumor. Tissue was microdissected from a hematoxylin and eosin-stained FFPE section (A) (dotted lines show the microdissected area), tumor proteins were extracted and analyzed by MS and compared to the patient's platelet proteome. (B) Illustrates the overlapping of platelet and tumor proteomes. (C) Integrin alpha-IIb (also known as GPIIB or CD41) was detected immunohistochemically in the platelet-rich part of the patient's excised spleen (a) and tumor cells (b), but not in another patient's carcinoma cells (c) at low (top) and high magnification (bottom).
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F2
As postulated, integrin alpha-IIb (also known as GPIIB or CD41) was found among the 738 proteins identified in purified platelets (Figure 2B), and validated with 57 specific peptides. Surprisingly, integrin alpha-IIb was also found among the 422 proteins identified in the microdissected tumor (Figure 2A) and validated with 2 specific peptides, suggesting tumor aberrant alpha-IIb expression, which would have triggered anti-GPIIBIIIA autoantibody production. Pertinently, no blood vessels were detected in the histological preparation: we observed bright punctiform labeling in the platelet-rich zone of the patient's removed spleen (Figure 2Ca). Anti-CD41 antibody (diluted 1:50) diffusely labeled our patient's tumor cells (Figure 2Cb) but not the carcinoma cells from an anti-GPIIBIIIA antibody-negative patient (Figure 2Cc).