CD40-CD40L interactions are critical for controlling Pneumocystis infection. However, which CD40-expressing cell populations are important for this interaction have not been well-defined. We used a cohousing mouse model of Pneumocystis infection, combined with flow cytometry and qPCR, to examine the ability of different populations of cells from C57BL/6 mice to reconstitute immunity in CD40 knockout (KO) mice. Unfractionated splenocytes, as well as purified B cells, were able to control Pneumocystis infection, while B cell depleted splenocytes and unstimulated bone-marrow derived dendritic cells (BMDCs) were unable to control infection in CD40 KO mice. Pneumocystis antigen-pulsed BMDCs showed early, but limited, control of infection. Consistent with recent studies that have suggested a role for antigen presentation by B cells, using cells from immunized animals, B cells were able to present Pneumocystis antigens to induce proliferation of T cells. Thus, CD40 expression by B cells appears necessary for robust immunity to Pneumocystis.

中文翻译：

---

B 细胞表达 CD40 是对鼠肺孢子虫感染的最佳免疫力所必需的

CD40-CD40L 相互作用对于控制肺孢子虫感染至关重要。然而，哪些表达 CD40 的细胞群对于这种相互作用很重要尚未明确。我们使用肺孢子虫感染的同居小鼠模型，结合流式细胞术和 qPCR，检测 C57BL/6 小鼠不同细胞群在 CD40 敲除 (KO) 小鼠中重建免疫的能力。未分级的脾细胞以及纯化的 B 细胞能够控制肺孢子虫感染，而 B 细胞耗尽的脾细胞和未刺激的骨髓来源的树突状细胞 (BMDC) 无法控制 CD40 KO 小鼠的感染。肺孢子菌抗原脉冲的 BMDC 显示出早期但有限的感染控制。与最近表明 B 细胞抗原呈递作用的研究一致，使用来自免疫动物的细胞，B 细胞能够呈递肺孢子虫抗原以诱导 T 细胞增殖。因此，B 细胞表达 CD40 似乎是对肺孢子虫的强大免疫所必需的。