Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15261, U.S.A.
Biochem J. 2021 Nov 26;478(22):3999-4004. doi: 10.1042/BCJ20210652.
Tim-3 is a transmembrane protein that is highly expressed on subsets of chronically stimulated CD4+ helper and CD8+ cytotoxic T cells, with more transient expression during acute activation and infection. Tim-3 is also constitutively expressed by multiple types of myeloid cells. Like other TIM family members, Tim-3 can bind to phosphatidylserine displayed by apoptotic cells, and this interaction has been shown to mediate uptake of such cells by dendritic cells and cross-presentation of antigens to CD8+ T cells. In contrast, how the recognition of PS by Tim-3 might regulate the function of Tim-3+ T cells is not known. In their recent paper, Lemmon and colleagues demonstrate for the first time that recognition of PS by Tim-3 leads to enhanced T cell activation.
TIM-3 是一种跨膜蛋白，在慢性刺激的 CD4+辅助性 T 细胞和 CD8+细胞毒性 T 细胞亚群上高度表达，在急性激活和感染期间也有短暂表达。TIM-3 还由多种类型的髓样细胞组成性表达。像其他 TIM 家族成员一样，TIM-3 可以与凋亡细胞上展示的磷脂酰丝氨酸结合，并且已经表明这种相互作用介导树突状细胞摄取此类细胞以及将抗原交叉呈递给 CD8+T 细胞。相比之下，TIM-3 识别 PS 的方式如何调节 TIM-3+T 细胞的功能尚不清楚。在他们最近的论文中，Lemmon 及其同事首次证明，TIM-3 识别 PS 可导致 T 细胞激活增强。
