Role of B cells in the Cell-Mediated Immune Response to Leishmania amazonensis

描述（由申请方提供）：利什曼病是一种媒介传播的人畜共患病，在中东、亚洲、非洲和中美洲流行。感染硕大利什曼原虫的C3 HeB/FeJ（C3 H）小鼠产生CD 4 + TH 1应答并解决感染，而感染亚马逊利什曼原虫刺激较差的T细胞应答，导致慢性疾病。当C3 H小鼠共感染两种利什曼原虫时，我们观察到与感染利什曼原虫相似的愈合表型。少校独自一人。相反，共感染的C57 BL/6（B6）小鼠具有与L.亚马逊河。我们已经开发了一种体外试验，发现引流淋巴结L.置于该transwell测定中的主要感染的C3 H小鼠对于巨噬细胞活化和L.亚马逊河。当 B6小鼠来源的总淋巴结细胞或纯化的CD 4 + T细胞和B细胞来自感染L. major与L.没有观察到亚马逊感染的巨噬细胞杀死寄生虫。一系列的细胞转移研究表明，来自B6小鼠的B细胞不促进细胞内L.亚马逊河。体外寄生虫杀伤试验和体内转移试验的这些发现表明，B细胞在细胞介导的抗L. amazonensis，并且与来自CSH小鼠的细胞相比，来自B6小鼠的B细胞不能促进巨噬细胞寄生虫杀死。关于C3 H和B6 B细胞之间的差异，我们提出了两种假设。首先，我们假设来自C3 H小鼠的B细胞产生促炎细胞因子，其积极影响CD 4 + T细胞以激活共感染的巨噬细胞，而来自B6小鼠的B细胞产生抗炎细胞因子，其消极影响CD 4 + T细胞以激活感染的巨噬细胞。我们的第二个假设是B6小鼠产生的新型抗体同种型IgG 2c可能不足以通过Fc γ受体刺激感染的巨噬细胞。 本提案中的工作将1）通过表征B细胞的表型来确定来自C57 BL/6小鼠的B细胞在共感染期间是否不充分地刺激生产性Th 1免疫应答;和2）确定B6 B细胞的IgG 2c产生是否改变巨噬细胞活化。这项工作的结果将强调B细胞在利什曼原虫感染中的重要性，所有这些都将为动物和人类皮肤利什曼病的治疗和疫苗选择的发展提供基础。这些发现也将促进我们对利什曼病遗传易感性的理解。

DESCRIPTION (provided by applicant): Leishmaniasis is a vector-borne zoonotic disease endemic to the Middle East, Asia, Africa and Central America. C3HeB/FeJ (C3H) mice infected with Leishmania major develop a CD4+ TH1 response and resolve infection, while infection with Leishmania amazonensis stimulates a poor T cell response, resulting in chronic disease. When C3H mice are co-infected with both species of Leishmania we observe a healing phenotype similar to infection with L. major alone. In contrast, co-infected C57BL/6 (B6) mice have a non-healing phenotype similar to infection with L. amazonensis. We have developed an in vitro assay and have found that CD4+ T cells and B cells from the draining lymph node L. major-infected C3H mice placed in this transwell assay are sufficient and necessary for macrophage activation and killing of L. amazonensis. When B6 mouse-derived total lymph node cells or purified CD4+ T cells and B cells from a B6 mouse infected with L. major are co-cultured in vitro with L. amazonensis infected macrophages parasite killing is not observed. A series of cell transfer studies have demonstrated that B cells from the B6 mice do not promote killing of intracellular L. amazonensis. These findings from our in vitro parasite killing assay and in vivo transfer experiments indicate that B cells play a prominent role in the cell mediated immune response against L. amazonensis and that B cells from B6 mice are unable to promote macrophage parasite killing compared to cells from CSH mice. We have generated two hypotheses concerning the difference between C3H and B6 B cells. First, we hypothesize B cells from C3H mice produce pro-inflammatory cytokines that positively influence CD4+ T cells to activate co-infected macrophages, while B cells from B6 mice produce anti-inflammatory cytokines that negatively influence CD4+ T cells to activate infected macrophages. Our second hypothesis is the production of the novel antibody isotype lgG2c by B6 mice may inadequately stimulate infected macrophages via the Fc gamma receptors. The work in this proposal will 1) establish if B cells from C57BL/6 mice inadequately stimulate a productive Th1 immune response during co-infection by phenotypically characterizing B cells; and 2) determine if lgG2c production by B6 B cells alters macrophage activation. Results of this work will emphasize the importance of B cells in Leishmania infection and all will provide a foundation for development of treatment and vaccine options of cutaneous leishmaniasis in animals and humans. These findings will also advance our understanding of genetic predispositions to leishmaniasis.