Correlation between the CD8+ T cell/IFN-γ axis and clinical disease progression at different phases of ITP.

BACKGROUND: Primary immune thrombocytopenia (ITP) represents the most common acquired bleeding disorder among children. Since its immune mechanism is not fully clarified, precise immune markers still need to be identified for guiding and intervening in recurrent and refractory cases. METHODS: This cross-sectional study included children diagnosed with ITP between August 2022 and November 2024. Peripheral blood levels of CD3+ T, CD4+ T, CD8+ T, and B cells were quantified via flow cytometry analysis. Intracellular IFN-γ expression was analyzed. Spearman correlation analysis was conducted in combination with platelet count and WHO bleeding score. RESULTS: Compared with healthy controls, children with ITP exhibited a markedly reduced platelet count and elevated bleeding frequency (both P < 0.0001). The proportion of CD8+ T cells significantly increased in both the relapse group and the severe group, and the CD4+/CD8+ ratio decreased in the severe group. The proportions of CD3-IFN-γ cells, CD4+ IFN-γT cells, and CD8+ IFN-γT cells were all higher in ITP children than in healthy controls, with higher CD3+ CD8+ IFN-γT cells expression detected in the severe group (all P < 0.05). Platelet was negatively correlated with the proportion of CD3+ CD8+ IFN-γT cells (r = -0.2583, P = 0.012). CONCLUSION: Aberrant activation of the CD8+ T cell/IFN-γ axis is closely associated with thrombocytopenia, disease recurrence, and severity in pediatric ITP, and may serve as a potential immune-targeted intervention candidate for refractory ITP.