MHC and MHC-like molecules: structural perspectives on the design of molecular vaccines

Major histocompatibility complex (MHC) molecules bind and present short antigenic peptide fragments on the surface of antigen presenting cells (APCs) to T-cell receptors. Recognition of peptide-MHC complexes by T-cells initiates a cascade of signals in T-cells and activated cells either destroy or help to destroy the APC. The MHCs are divided into three subgroups: MHC class I, MHC class II and MHC class III. In addition, nonclassical MHC molecules and MHC-like molecules play a pivotal role in shaping our understanding of the immune response. In the design of molecular vaccines for the treatment of diseases, an understanding of the three-dimensional structure ofMHC, its interaction with peptide ligands and its interaction with the T-cell receptor are important prerequisites, all of which are discussed herein.