期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2002
卷号：99
期号：13
页码：8844-8849
DOI：10.1073/pnas.092260499
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We examine here the nature of the differential recognition by CD4+ T cells of a single peptide from hen-egg white lysozyme (HEL) presented by I-Ak class II MHC molecules. Two subsets of T cells (called A and B) interact with the same peptide, each in unique ways that reflect the nature of the complex of peptide and MHC. We show that the A and B set of T cells can be distinguished by their functional interaction with the three T cell receptor (TCR) contact residues of the bound peptide. The dominant peptide of HEL selected from processing is bound in a single register where a critical TCR contact residue is situated about the middle of the core segment of the peptide: all T cells establish functional contact with it. Three sets of T cells, however, can be distinguished by their differential recognition of two TCR contacts situated at the amino and carboxyl sides of the central TCR contact residue. Type A T cells, the conventional cells that see the peptide after processing of HEL, need to recognize all three TCR contact residues. In contrast, the type B T cells recognize the peptide given exogenously, but not when processed: these T cells recognize either one of the peripheral TCR contact residues, indicating a much more flexible interaction of peptide with I-Ak molecules. We discuss the mode of generation of the various T cells and their biological relevance.
