IMMUNOLOGY

Detailed explanation-1: -The major histocompatibility (MHC) class I antigen presentation pathway plays an important role in alerting the immune system to virally infected cells. MHC class I molecules are expressed on the cell surface of all nucleated cells and present peptide fragments derived from intracellular proteins.

Detailed explanation-2: -Viral (or other) antigens produced inside of cells are proteolytically processed and are presented on the surface of the cell. Antigens are presented by a set of cell surface proteins called major histocompatibility (MHC) proteins (Fig. 6.6).

Detailed explanation-3: -There are two major types of MHC protein molecules-class I and class II. Class I MHC molecules span the membrane of almost every cell in an organism, while class II molecules are restricted to cells of the immune system called macrophages and lymphocytes.

Detailed explanation-4: -MHC Class II molecules are a class of major histocompatibility complex (MHC) molecules normally found only on professional antigen-presenting cells such as dendritic cells, mononuclear phagocytes, some endothelial cells, thymic epithelial cells, and B cells.

Detailed explanation-5: -The human leukocyte antigen (HLA) system (the major histocompatibility complex [MHC] in humans) is an important part of the immune system and is controlled by genes located on chromosome 6. It encodes cell surface molecules specialized to present antigenic peptides to the T-cell receptor (TCR) on T cells.