Structural basis of T cell recognition of peptides bound to MHC molecules

Helper T lymphocytes play a critical role in immune system activation following recognition of MHC class II-bound peptide ligands (pMHCII). These CD4 T cells stimulate B cell antibody production and cytolytic T cell generation. Until recently. the structural basis of coordinate T cell receptor (TCR) and CD4 co-receptor interaction with a given was unknown. Here we review current structural data on specific pMHCII recognition by T cells and compare TCR and co-receptor docking to pMHCI versus pMHCII ligands. The implications of these findings for thymic selection. helper versus cytoltic T cell recognition and alloreactivity are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.