[Analysis of Frequencies and Subsets of Peripheral Helper T Cells in Patients with Immune Thrombocytopenia].

Objective: To investigate the frequencies and subset distribution of peripheral helper (Tph) T cells in patients with immune thrombocytopenia (ITP), and explore the pathogenesis of ITP.

Methods: A total of 25 newly diagnosed ITP patients treated in The Second Affiliated Hospital of Dalian Medical University from January to December 2022 were selected, and 25 healthy volunteers (age- and sex-matched) were recruited as the control group. Flow cytometry was used to detect the subsets of CD4 T cells and Tph cells.

Results: The frequency of effector memory (CCR7 CD45ROCD4) T cells in ITP patients was significantly higher than that in healthy controls( < 0.05). The frequency of Tph cells in ITP patients was also significantly higher than that in healthy controls ( < 0.001), and most of the Tph cells in ITP patients were effector memory T cells. Furthermore, the expressions of T-cell costimulatory molecules in Tph cells, including ICOS and CD84, were similar to those in follicular helper T(Tfh) cells. CXCR3 CCR6 Tph (Tph2) subgroup was dominant in Tph cells, but the frequency of CXCR3CCR6 Tph (Tph1) cells in ITP patients was much higher than that in healthy controls ( < 0.05).

Conclusion: Tph cells, especially Tph1 cells, were abnormally expanded in ITP patients, which may be a potential etiology of ITP.