Malnati M S, Marti M, LaVaute T, Jaraquemada D, Biddison W, DeMars R, Long E O
Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852.
Nature. 1992 Jun 25;357(6380):702-4. doi: 10.1038/357702a0.
Antigens presented to CD4+ T cells derive primarily from exogenous proteins that are processed into peptides capable of binding to class II major histocompatibility complex (MHC) molecules in an endocytic compartment. In contrast, antigens presented to CD8+ T cells derive mostly from proteins processed in the cytosol, and peptide loading onto class I MHC molecules in an early exocytic compartment is dependent on a transporter for antigen presentation encoded in the class II MHC region. Endogenous cytosolic antigen can also be presented by class II molecules. Here we show that, unlike class I-restricted recognition of antigen, HLA-DR1-restricted recognition of cytosolic antigen occurs in mutant cells without a transporter for antigen presentation. In contrast, DR1-restricted recognition of a short cytosolic peptide is dependent on such a transporter. Thus helper T-cell epitopes can be generated from cytosolic antigens by several mechanisms, one of which is distinct from the classical class I pathway.
呈递给CD4+ T细胞的抗原主要来源于外源性蛋白质，这些蛋白质在内吞小室中被加工成能够与II类主要组织相容性复合体（MHC）分子结合的肽段。相比之下，呈递给CD8+ T细胞的抗原大多来源于在细胞质中加工的蛋白质，并且在早期胞吐小室中肽段加载到I类MHC分子上依赖于II类MHC区域编码的抗原呈递转运体。内源性胞质抗原也可由II类分子呈递。我们在此表明，与I类限制的抗原识别不同，HLA-DR1限制的胞质抗原识别发生在没有抗原呈递转运体的突变细胞中。相比之下，DR1限制的短胞质肽识别依赖于这样一种转运体。因此，辅助性T细胞表位可通过多种机制从胞质抗原产生，其中一种机制不同于经典的I类途径。
