Detailed Immunological Characterization of Platelet Recovery in Refractory Pediatric <scp>ITP</scp> : A Case Report

An 8-year-and-5-month-old female patient was diagnosed with immune thrombocytopenia (ITP) at an external hospital in May 2021, with bone marrow cytology findings consistent with ITP. Her platelet (PLT) count reached a nadir of 7 × 109/L. Initial treatment with intravenous immunoglobulin (IVIG) and glucocorticoids to block antibody-mediated destruction yielded a suboptimal response, with PLT counts stabilizing at approximately 30 × 109/L. In November 2021, therapy was escalated to the thrombopoietin receptor agonist (TPO-RA) eltrombopag. Owing to inadequate efficacy, this treatment was switched to avatrombopag in September 2024. Following a persistent insufficient platelet response, combination therapy with rituximab (anti-CD20 monoclonal antibody, RTX) and traditional Chinese medicine (TCM) was initiated in November 2024. By December 2024, subsequent monitoring demonstrated restoration and sustained maintenance of PLT counts within the normal range, peaking at 711 × 109/L (Figure 1). The herbal formulas consistently aimed to harmonize Qi and blood and soothe the liver and fortify the spleen as the core therapeutic objective, supplemented with adjunctive treatments such as calming the spirit (e.g., Poria cum Radix Pini [Fushen], Lilii Bulbus [Baihe]) and clearing heat (e.g., Scutellariae Radix [Huangqin], Puerariae Lobatae Radix [Gegen]). Core therapeutic strategy: All formulas emphasize Qi tonification (Huangqi, Baizhu) and blood regulation (Danggui, Baishao). Liver-Spleen harmonization (Chaihu, Gancao) and heat clearing (Huangqin) were consistently maintained. (1) Early stages feature blood-activating (Chishao) and bleeding-stopping herbs (Xianhecao); (2) Middle/late stages introduce kidney–Yang tonics (Bajitian, Buguzhi), and immune-modulating (Lingzhi) collateral-dredging herbs (Chuanshanlong) appear consistently after November 2024; Yang-lifting herbs (Gegen, Shengma) are used intermittently. All the formulas were administered as water decoctions for oral use. The frequency decreased from near-continuous (6 days on/1 day off) to intermittent (2 days on/1 day off, then every other day). The patient underwent detailed immune phenotyping monitoring in July 2024, October 2024, and February 2025. Analysis of the results before and after PLT count recovery, including detailed T-cell and B-cell phenotypes, revealed the following (Figure 2). Among CD8+ T cells, the expression of the activation markers CD38 and HLA-DR was assessed. Following treatment, HLA-DR expression tended to decrease. This change may reflect an alteration in the activation status of CD8+ T cells during therapy (Figure 2A). Naïve Tregs (nTreg, CD45RA+ Tregs) and induced Tregs (iTreg, CD45RA− Tregs) play crucial roles in immune regulation. This study revealed an increasing trend in the proportions of both nTregs and iTregs as treatment progressed. These findings suggest that therapy may promote the proliferation or differentiation of regulatory T cells, contributing to the reshaping of immune homeostasis (Figure 2B). Regulatory B cells (Bregs; CD19+CD24++CD38++) increased significantly. Concurrently, plasmablast levels (CD38+CD24−) declined, potentially due to therapy-induced effects on B-cell differentiation. Furthermore, the numbers of memory B cells (CD19+CD27+IgD+) and class-switched memory B cells (CD19+IgD−IgM−CD27+) also tended to decrease. These shifts collectively reflect the regulatory impact of treatment on key B-cell subsets, particularly regulatory B cells, memory subsets, and class-switched B cells, concurrently participating in the remodelling of immune homeostasis (Figure 2C,D). Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by accelerated platelet destruction and impaired megakaryopoiesis, leading to bleeding diathesis. While first-line therapies (corticosteroids and IVIGs) and second-line agents (TPO-RAs, rituximab) demonstrate efficacy, significant limitations exist: Corticosteroids include long-term toxicity (osteoporosis, hyperglycemia) with frequent relapse (up to 30%–50% in chronic ITP) [1, 2]. IVIG provides a transient response but is costly and carries renal/cardiovascular risks [3]. TPO-RAs have a variable response (60%–80% initial response) with thrombosis concerns [4]. Immunosuppressants (e.g., cyclosporine) exhibit narrow therapeutic windows and organ toxicity. Refined lymphocyte subset analysis offers critical insights for therapeutic optimization: T-cell profiling: Depleted/dysfunctional Tregs (particularly CD45RA+ nTregs) correlate with loss of immune tolerance. Elevated HLA-DR+CD38+ activated CD8+ T cells drive platelet cytotoxicity. Monitoring Treg reconstitution (e.g., postsirolimus/low-dose decitabine) predicts a sustained response [5, 6]. B-cell dynamics: The expansion of class-switched memory B cells and plasmablasts perpetuates antiplatelet antibody production. Breg deficiency exacerbates humoral autoimmunity [7]. Targeted B-cell therapies (e.g., FcRn antagonists and proteasome inhibitors) reduce pathogenic subsets while preserving regulatory function. The integration of traditional medicine with immunophenotyping holds promise: herbal compounds (e.g., Astragalus-derived saponins and Angelica polysaccharides) may modulate the Treg/Breg balance and suppress memory B-cell differentiation. Longitudinal subset analysis (Treg/Breg ratios, plasmablast kinetics) provides objective metrics for efficacy assessment, as seen in cases where herbal intervention correlated with an increased frequency of Tregs (≥ 2.5% CD4+ T cells) and a decreased percentage of CD27+IgD− class-switched memory B cells, which stabilized platelets (≥ 50 × 109/L) [8, 9]. Combining refined immunomonitoring (e.g., PD-1/CTLA-4 expression and B-cell maturation staging) with novel agents (Syk/BTK inhibitors and FcRn blockers) or phytomedicines enables precision management of refractory ITP. Future studies should validate subset-driven treatment algorithms to overcome therapeutic resistance [10]. This case illustrates the potential of TCM-Western integration guided by immune phenotyping to achieve remission in a pediatric ITP, which suggests potential efficacy and is potentially linked to immune homeostasis remodelling [1, 10]. This case study comprehensively evaluated dynamic changes in T-cell and B-cell subpopulations, providing a holistic reflection of immune system dynamics and may offer insights for future personalized treatment approaches. The patient's response falls within the expected range for rituximab monotherapy in pediatric ITP. The immunologic alterations observed in this case—including increases in Tregs and Bregs and decreases in activated CD8+ T cells—are consistent with known effects of RTX. Following rituximab administration, B cell reconstitution may be observed alongside an expansion of regulatory B cells and shifts in T-cell populations, including alterations in Treg frequencies [11]. It has been pointed out that RTX exerts its effect through elimination of B cells: the subsequent repopulation of B cells generates a predominance of Breg cells (CD5+ B cells), restoring the numerical balance between Breg and memory B cells 12 months after RTX administration [12]. The mechanism of integrated Chinese and Western medicine treatment (TCM + RTX) likely involves both rituximab-mediated B-cell depletion and possible immunomodulatory effects of TCM, leading to reduced platelet destruction and improved immune balance, manifesting as increased Breg level observed at 2 months after RTX injection. While TCM may have contributed to immune modulation, its individual role cannot be disentangled from that of RTX in this setting. Besides, the progressive modification of herbal formulas reflects real-world TCM practice but precludes attribution of specific immune changes to particular herbal components. Therefore, the specific contribution of TCM to immune remodeling or platelet recovery remains uncertain and would require comparative study designs to elucidate. It is important to note that this report describes the experience of a single pediatric patient at one center. Therefore, the findings cannot be generalized, and the observed platelet recovery following treatment does not establish causation. These observations are hypothesis-generating and require validation in larger, controlled studies. In summary, incorporating refined lymphocyte subset analysis into ITP treatment evaluation enables deeper insights into immune dysregulation mechanisms. This approach provides a critical foundation for optimizing therapeutic regimens, enhancing treatment efficacy, and improving patient prognosis. It may hold value for assessing the efficacy and mechanisms of both conventional and herbal medicine therapies. Liping Luo, Xiaoying Fu and Ying Wang were responsible for data collection, analysis, interpretation, and writing of the manuscript; Qian Li, Yuyang Zhao, Zhaonan Liu and Yaxian Kuang provided the patient data collection; Xiaoying Fu and Ying Wang provided the clinical and funding support. All authors reviewed and critiqued the manuscript. This work was supported by the Guangdong High-level Hospital Construction Foundation (No. ynkt2021-zz05), the Shenzhen Science and Technology Research Foundation (No. JCYJ20210324142201004), and the Shenzhen Children's Hospital Science and Technology Foundation (No. ynkt2020-zz04). This study was approved by the ethics committee of Shenzhen Children's Hospital (Shenzhen Children's Hospital Ethics Committee (Research) Approval Notice No. 202501202), and informed consent for publication was obtained from the parents of the individual participants in the study. Informed consent for publication was obtained from the parents of the individual participants in the study. The authors declare no conflicts of interest. The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.