Antigen processing and presentation are the cornerstones of adaptive immunity. B cells cannot generate high-affinity antibodies without T cell help. CD4⁺ T cells, which provide such help, use antigen-specific receptors that recognize major histocompatibility complex (MHC) molecules in complex with peptide cargo. Similarly, eradication of virus-infected cells often depends on cytotoxic CD8⁺ T cells, which rely on the recognition of peptide–MHC complexes for their action. The two major classes of glycoproteins entrusted with antigen presentation are the MHC class I and class II molecules, which present antigenic peptides to CD8⁺ T cells and CD4⁺ T cells, respectively. This Review describes the essentials of antigen processing and presentation. These pathways are divided into six discrete steps that allow a comparison of the various means by which antigens destined for presentation are acquired and how the source proteins for these antigens are tagged for degradation, destroyed and ultimately displayed as peptides in complex with MHC molecules for T cell recognition.

抗原加工和呈递是适应性免疫的基石。没有 T 细胞的帮助，B 细胞无法产生高亲和力的抗体。提供这种帮助的CD4 ⁺ T 细胞使用抗原特异性受体识别与肽货物复合的主要组织相容性复合体 (MHC) 分子。同样，病毒感染细胞的根除通常依赖于细胞毒性 CD8 ⁺ T 细胞，这些细胞的作用依赖于肽-MHC 复合物的识别。负责抗原呈递的两大类糖蛋白是 MHC I 类和 II 类分子，它们将抗原肽呈递给 CD8 ⁺ T 细胞和 CD4 ⁺T细胞，分别。本综述描述了抗原加工和呈递的要点。这些途径分为六个不连续的步骤，这些步骤允许比较获取用于呈递的抗原的各种方式，以及这些抗原的来源蛋白质如何被标记为降解、破坏并最终显示为与 T 的 MHC 分子复合的肽细胞识别。