Quantity and function of T follicular helper cells in the bone marrow of patients with immune thrombocytopenia

Abstract

This study was purposed to detect the quantity and function of bone marrow (BM) T follicular helper (Tfh) cells of patients with immune thrombocytopenia, and to explore the role of Tfh cells in the pathogenesis of ITP. Twenty-one newly diagnosed ITP patients, twenty ITP patients in recovery stage and eighteen normal controls were enrolled in this study. The percentages of Tfh cells, Tfh-related molecules ICOS, CD40L, IL-21 in BM were detected by flow cytometry (FCM), and the mRNA expression of BCL-6 in BMMNC was determined by semi-quantitive RT-PCR. Correlation of Tfh cell level with the disease severity of ITP patients was analysed. The results showed that the ratio of CD4(+)CXCR5(+)/CD4(+) cells in newly diagnosed ITP patients [(5.532 ± 2.599)%] was significantly higher than that in ITP patients with recovery stage [(4.064 ± 2.026)%] and controls [(4.048 ± 1.413)%] (P < 0.05). The ratio of CD4(+)CXCR5(+)ICOS(+)/CD4(+) CXCR5(+) cells in newly diagnosed ITP patients [(14.586 ± 8.561)%] was higher than that in recovery stage ITP patients [(12.884 ± 10.161)%] and controls [(7.487 ± 5.176)%]. The differences be-tween newly diagnosed ITP patients and controls were statistically significant (P < 0.05). The ratio of CD4(+)CXCR5(+) CD40L(+)/CD4(+) CXCR5(+) cells in newly diagnosed ITP patients [(15.309 ± 10.756)%] and in ITP patients with recovery stage [(18.242 ± 12.243)%] were significantly higher than that in controls [(8.618 ± 5.719) %] (P < 0.05). The ratio of intracytoplasm CD4(+) CXCR5(+) IL-21(+)/CD4(+)CXCR5(+) cells in newly diagnosed ITP patients [(58.560 ± 26.285)%] and in ITP patients with recovery stage [(57.035 ± 30.936)%] were significantly higher than that in controls [(36.289 ± 24.868)%] (P < 0.05). The relative expression levels of BCL-6 mRNA in BMMNC of three groups were (1.407 ± 0.264), (1.149 ± 0.217) and (0.846 ± 0.157), respectively. The differences between 3 groups were significant(P < 0.05). It is concluded that the quantity and function of Tfh cells in ITP patients increase, which may play an important role in the pathogenesis of ITP.