Аннотация:Antigen presentation is a process that allows T cells to recognize antigenic epitopes displayed on the surface of an antigen-presenting cell. Antigen presentation involves a sophisticated process of epitope preparation, i.e., processing which involves cellular machinery designed for general purposes (e.g., ubiquitination complex and proteasomes) and molecules specific for the presentation pathways. Key molecules providing antigen display are major histocompatibility complex class I and class II which are highly polymorphic and have many allelic variants. Major function of this molecules is regarded as initiation of adaptive immunity via recruiting and activation of antigen-specific CD4 and CD8 T cells. However, MHC class I and class II are also essential for T cell development and immune tolerance. Antigen processing impairment may result in an autoimmune disease or an immunodeficiency. Pathogens have evolved multiple immune evasion strategies involving MHC presentation pathways.