T细胞在抵抗感染的适应性免疫反应中发挥着至关重要的作用,是宿主免疫系统的关键组成部分。在MHC分子递呈下,外源抗原接触T细胞受体(TCR)从而启动初始T细胞(naive T cell)激活,并且这种激活也需要诸如CD28之类的共刺激分子(costimulatory molecule)的参与。这种TCR-CD28共刺激触发信号事件级联反应,启动T细胞的激活和随后的分化。T细胞激活后会引发T细胞介导的免疫反应,这会有效地清除入侵的病原体和发生病变的细胞,同时也通过区分自我抗原和外源抗原,避免 T cells play a crucial role in the adaptive immune response against infection and are a key component of the host’s immune system. At the MHC molecule presentation, the foreign antigen contacts the T cell receptor (TCR) to initiate naive T cell activation and this activation also requires the participation of a costimulatory molecule such as CD28 . This TCR-CD28 costimulation triggers a cascade of signaling events that initiates T cell activation and subsequent differentiation. T-cell activation triggers a T cell-mediated immune response that effectively removes invading pathogens and diseased cells as well as avoiding differentiation between self-antigens and foreign antigens