Th9 Cells in Peripheral Blood Increased in Patients with Immune-Related Pancytopenia

Background: Immune-related pancytopenia (IRP) is a kind of autoimmune disease mediated by autoantibodies in bone marrow. T helper 9 (Th9) cell is a new subset of T cell discovered recently, which mainly expresses cytokine interleukin-9 (IL-9) to exert immune function. Th9 cells are associated with a variety of inflammatory diseases, but the role of Th9 cells in IRP remains unclear.

Methods: Fifty patients with IRP and 20 healthy controls were enrolled. The percentage of Th9 cells was detected by flow cytometry (FCM) and ELISA. CD4⁺ lymphocytes were sorted by magnetic beads, and the mRNA expression levels of Th9 cells related transcription factors PU.1 and BATF were detected by RT-PCR.

Results: The percentage of Th9 cells in CD3⁺CD4⁺ cells was 2.73 ± 1.96% in the untreated group, which was significantly higher than those in the remission group (1.21 ± 0.86%) (p < 0.01) and the control group (0.68 ± 0.40%) (p < 0.001). And that in the remission group was significantly higher than that in the control group (p < 0.05). The level of IL-9 in the untreated group was 183.91 ± 112.42 pg/mL, which was significantly higher than that in the remission group (105.96 ± 64.79 pg/mL) (p < 0.01) and control group (56.03 ± 14.49 pg/mL) (p < 0.001). That in the remission group was also significantly higher than that in the control group (p < 0.01). They were negatively correlated with hemoglobin, red blood cell, white blood cell, and platelet counts and positively correlated with the percentage of CD19⁺B cells and CD5⁺CD19⁺/CD19⁺B cells, respectively. The mRNA expression levels of PU.1 and BATF in IRP patients were higher than those in controls (p < 0.05).

Conclusions: The percentage of Th9 cells in the peripheral blood and the level of IL-9 in the serum of patients with IRP were increased, which was related to the severity of the disease.