Interleukin 9 (IL-9) is an effective cytokine secreted by newly defined Th9 cells, which is involved in allergic and infectious diseases. In this study, lymphocytes were isolated from mesenteric lymph node (MLN), spleen, liver, lung, and Peyer’s patches (PP) of C57BL/6 mice 5–6 weeks after S. japonicum infection, intracellular cytokine staining was done to detect the percentage of IL-9-producing CD4⁺ T cells. The qPCR and ELISA were used to verify the content of IL-9 in MLN. The population of IL-9-producing lymphocyte subset was identified by FACS. In addition, the dynamic changes and cytokine profiles of Th9 cells in the MLN of infected mice were detected by FACS. ELISA was used to detect IL-9 induced by soluble egg antigen (SEA) from isolated lymphocytes in mouse MLN. The results showed that the percentage of IL-9-secreting Th9 cells in the MLN of the infected mouse was higher than that in the spleen, liver, lung, or PP. Though CD8⁺ Tc cells, NKT cells, and γδT cells could secrete IL-9, CD4⁺ Th cells were the main source of IL-9 in S. japonicum-infected C57BL/6 mice (P < 0.05). The percentage of Th9 cells in MLN of infected mouse increased from week 3–4, and reached a peak at week 5–6, then began to decrease from week 7–8 (P < 0.05). Moreover, Th9 cells could also secrete a small amount of IL-4, IFN-γ, IL-5, and IL-10. Our results suggested a higher percentage of Th9 cells was induced in the MLN of S. japonicum-infected mice, which might play an important role in the early stage of S. japonicum-induced disease.

白细胞介素 9 (IL-9) 是由新定义的 Th9 细胞分泌的一种有效细胞因子，它与过敏和传染病有关。本研究在日本血吸虫感染 5-6 周后，从 C57BL/6 小鼠的肠系膜淋巴结 (MLN)、脾脏、肝脏、肺和淋巴集结 (PP) 中分离淋巴细胞，进行细胞内细胞因子染色检测产生 IL-9 的 CD4 ⁺ T 细胞的百分比。qPCR和ELISA用于验证MLN中IL-9的含量。产生 IL-9 的人群淋巴细胞亚群通过 FACS 鉴定。此外，FACS 检测了受感染小鼠 MLN 中 Th9 细胞的动态变化和细胞因子谱。ELISA 用于检测小鼠 MLN 中分离的淋巴细胞的可溶性卵抗原 (SEA) 诱导的 IL-9。结果表明，受感染小鼠的 MLN 中分泌 IL-9 的 Th9 细胞的百分比高于脾脏、肝脏、肺或 PP。虽然 CD8 ⁺ Tc 细胞、NKT 细胞和 γδT 细胞可以分泌 IL-9，但 CD4 ^{+ Th 细胞是}日本血吸虫感染的 C57BL/6 小鼠IL-9 的主要来源（ P  < 0.05）。感染小鼠MLN中Th9细胞的百分比从第3-4周开始增加，并在第5-6周达到峰值，然后从第7-8周开始下降（P  < 0.05）。此外，Th9细胞还可以分泌少量的IL-4、IFN-γ、IL-5和IL-10。我们的结果表明，在日本血吸虫感染的小鼠的 MLN 中诱导了更高百分比的 Th9 细胞，这可能在日本血吸虫引起的疾病的早期阶段发挥重要作用。