MHC Series Proteins

The Major Histocompatibility Complex (MHC) is a group of proteins located on the surface of cells, whose primary function is to present antigen fragments to T cells. This process is crucial for the immune system's ability to recognize and eliminate infections. MHC is divided into two classes: MHC class I molecules are present on the surface of almost all nucleated cells. They display fragments of proteins produced internally (such as viral proteins or tumor proteins) to CD8+ T cells (cytotoxic T cells). This helps the immune system detect and eliminate infected or cancerous cells. MHC class II molecules are primarily expressed on the surface of professional antigen-presenting cells in the immune system, such as dendritic cells, macrophages, and B cells. They present antigen fragments from the extracellular environment to CD4+ T cells (helper T cells), thereby initiating and regulating the immune response.