Follicular T helper cells: critical regulators of humoral immune responses

B细胞是免疫系统的重要细胞，其负责响应于病原体如细菌或病毒的感染或在接种疫苗后产生抗体。为了让B细胞完成这项任务，它们需要一群专门的T细胞的帮助，T细胞是另一种类型的免疫细胞-这些细胞被称为滤泡T辅助细胞（TFH）。在正常情况下，T细胞和B细胞在淋巴组织（如扁桃体、脾脏和淋巴结）中特异性地相互作用--在这里，它们进行对话，其最终结果是T细胞指示B细胞产生适当类型的抗体。然而，如果这一过程不受调节，T细胞可能提供太少或太多的帮助-这可能导致几种不同类型的免疫系统疾病，如免疫缺陷（即抗体产生不足，导致个体易受感染）或自身免疫（即产生能够识别宿主细胞的不适当类型的抗体，导致组织损伤和器官衰竭）。TFH细胞指导B细胞产生抗体的方法还不完全清楚。该项目将通过从人体扁桃体和脾脏等组织中取出TFH细胞进行详细检查，以确定TFH细胞执行这一重要功能的机制。在这样做的过程中，我们希望设计出能够在免疫缺陷的情况下改善TFH细胞功能或在自身免疫性疾病的情况下抑制TFH细胞功能的方法。

B cells are important cells of the immune system that are responsible for producing antibodies in response to infection with pathogens, such as bacteria or viruses, or following vaccinations. In order for B cells to accomplish this task, they require help from a specialised popualtion of T cells, which are another type of immune cell - these are known as follicular T helper (TFH) cells. Under normal circumstances, T cells and B cells specifically interact with one another within lymphoid tissues such as tonsils, spleens and lymph nodes - here, they engage in a dialogue, the end result of which is the B cells being instructed to produce the appropriate type of antibodies by T cells. However, if tis process is not regulated, the T cells can deliver too little of too much help - this can result in several different types of diseases of the immune system, such as immunodeficiencies (ie insufficient production of antibodies, resulting in individuals becoming susceptible to infections) or autoimmunity (ie production of inappropriate types of antibodies that can recognise cells of the host, resulting in tissue damage and organ failure). The means by which TFH cells instruct B cells to produce antibodies is not completely understood. This project will seek to determine the mechanism whereby TFH cells carry out this important function by performing detailed examination of them follwoing their removal from tissues such as human tonsils and spleens. In doing so, we hope to design approaches that will allow the function of TFH cells to be improved in cases of immunodeficiencies, or suppressed in situations of autoimmune diseases.