Background and Objective: Immune thrombocytopenia (ITP) is an autoimmune-mediated hemorrhagic disease. Anti-glycoprotein autoantibodies play a key role in the pathophysiology of ITP, but the relationship between platelet-specific antibodies and bleeding severity is unclear. This study aimed to analyze the relationship between anti-glycoprotein autoantibodies and bleeding severity in children with newly diagnosed ITP and platelet count <10×109/L. Method: This was a single-center prospective observational study that analyzed children with newly diagnosed ITP and platelet count <10×109/L between June 2018 and September 2021 at our hospital. The children were classified into the mild and severe groups based on the bleeding scores. The type and titer of anti-glycoprotein autoantibodies were detected using an ELISA kit (PAKAUTO). We analyzed the relationship between bleeding severity and anti-glycoprotein autoantibodies. Results: A total of 86 cases were enrolled, including 42 in the mild group and 44 in the severe group. Patients with anti-GPIIb/IIIa or anti-GPIb/IX antibodies suffered more severe bleeding than patients without them (c2=7.303, p=0.007; c2=3.875, p=0.049), but there was no significant difference between patients with or without anti-GPIa/IIa antibody (c2=0.745, p=0.388). When antibodies were analyzed together, patients with three antibodies suffered more severe bleeding than those without three antibodies (c2=5.053, p=0.025). Patients with higher antibody titer in the eluent, but not in the plasma, suffered more severe bleeding in all three antibodies (Z=-2.389, p=0.017; Z=-2.108, p=0.035; Z=-2.557, p=0.011). Conclusion: Anti-glycoprotein autoantibodies led to more severe bleeding in children under 18 years of age without drug treatment with newly diagnosed ITP and platelet count <10×109/L.

Objective: To analyze the effect of a novel second-line escalating treatment strategy (high-dose dexamethasone (HDD), low-dose rituximab to eltrombopag) for children with severe chronic immune thrombocytopenia (SCITP). Materials and Methods: This study was a single-center, retrospective cohort study. The second-line escalating strategy included 3 steps: Step I (6 courses high-dose dexamethasone: HDD), Step II (HDD combined with low-dose rituximab), and Step III (eltrombopag). Results: A total of 30 cases (18 males and 12 females) were included; the median age was 8.83 (1.42-13.9) year-old, the duration time of ITP was 20.5 (12.0-96.0) months, and the platelet counts were 15 (3-29) ×109/L. After the median 14 (12-37) months’ treatment, the remission rate was 36.7% (11/30), and the sustained response (SR) rate was 68.2% (15/22). In eltrombopag (step III) cases, 47.5% (8/17) maintained platelet ≥50×109/L, 37.5% (3/8) dose tapering, and 25% (2/8) were successfully discontinued from medication. The number of patients at 12th, 24th, and 36th months was 30, 7, and 2, with the total response (TR) and remission rates of 80% (36.7%), 57.1% (28.6%), and 50% (50%), respectively. The total relapse rate was 26.7% (8/30)，three cases(75%, 3/4)from Step II and 5 cases (41.7% ,5/12)from Step III, none in Step I. Conclusion: The new second-line escalating strategy for children SCITP has an effective improving rate with 36.7% remission and 68.2% SR; 30% could benefit and retain stable response from HDD treatment. Combined treatment with eltrombopag can reduce the relapse rate of low-dose rituximab.