Thrombopoietin and its receptor expression in pediatric patients with chronic immune thrombocytopenia.

OBJECTIVES: Chronic immune thrombocytopenia (cITP) is common in children. However, the pathogenesis has not been fully elucidated. This study aimed to determine whether thrombopoietin (TPO) and its receptor c-mannosylation of the TPO receptor (c-Mpl) have an impact on childhood cITP. METHODS: Sixty-four patients with newly diagnosed ITP (nITP), 64 patients with persistent ITP, 80 patients with cITP, and 64 healthy children (control) were enrolled in this study. Plasma TPO was measured with an ELISA, and c-Mpl was determined by flow cytometry. RESULTS: Plasma TPO levels showed differences among the four groups (p = 0.001). TPO levels in the cITP group were significantly decreased compared to those in the nITP group (p < 0.05). The mean fluorescence intensity (MFI) of c-Mpl was significantly different among the four groups (p = 0.0275). c-Mpl MFI was lower in the cITP group than in the nITP group(p < 0.05). Quantitative real-time PCR analysis showed that TPO mRNA expression was higher in the control group than in the ITP groups (p < 0.0001). The c-Mpl mRNA levels also showed significant differences among the four groups (p = 0.023). The control group, compared with the other groups, had lower levels of c-Mpl mRNA. CONCLUSIONS: The expression of TPO and c-Mpl was significantly decreased in the cITP group compared to the nITP group, suggesting that TPO and its receptor may play important roles in childhood cITP pathogenesis.