OC 13.1 - Long-Term Impact of Splenectomy on Immune Status in Patients with ITP

Background: Splenectomy is the most effective long-term remission strategy for Immune Thrombocytopenia (ITP). However, concerns about invasiveness and postoperative infection risk lead to hesitation in choosing this treatment. The long-term impact on overall immune status remains unclear.

Aims: To evaluate the influence of splenectomy on immune status and predict the probability of mid-to-long-term infections.

Methods: The study included 27 ITP patients who underwent splenectomy. Peripheral blood mononuclear cells were collected from 8 patients before surgery and one-year post-surgery for single-cell sequencing. Additionally, peripheral blood samples were collected at various time points (preoperative, 1 week, 1 month, 3 months, 6 months, and 12 months postoperative) from all patients. Flow cytometry was used to assess lymphocyte subpopulations, ELISA measured plasma inflammatory factors, serum immunoglobulins and complement levels were also examined.

Results: (1) Post-splenectomy, CD19+B cells proportion in peripheral blood decreased, with a shift towards naive B cells. Gene set enrichment analysis showed upregulated functional pathways in various B cell subpopulations, and concentrations of immunoglobulins and complement in peripheral blood significantly increased postoperatively. (2) Th1 differentiation and cytotoxic T cell-associated gene sets were enriched in T cell subsets postoperatively. CD3+ T cell distribution shifted towards CD8+ T cells, and proportions of Th1, Th17, CD8+CD28- regulatory T cells, along with plasma perforin levels, increased. (3) Antigen presentation abilities of myeloid-derived cells decreased post-surgery but remained significantly higher than normal controls. Increased surface Fc receptors on monocytes were detected post-splenectomy. (4) Retrospective analysis over eight years showed a 7.8% infection rate in splenectomized patients, slightly lower than non-splenectomized ITP patients (12%).

Conclusion(s): Post-splenectomy, the immune system shifts towards enhanced cellular immunity, compensating for humoral immunity loss. Consequently, the long-term infection rate in post-splenectomy ITP patients is lower than expected.