Differentiate between antigenic epitope and the Major Histocompactibility Complex(MHC)
To differentiate between antigenic epitopes and the Major Histocompatibility Complex (MHC), let's first understand what each term means.
1. Antigenic Epitope:
- An antigen is a molecule that stimulates an immune response in the body. Antigenic epitopes, also referred to as antigenic determinants, are specific regions on an antigen to which antibodies or T-cell receptors bind.
- Epitopes can be either linear or conformational. Linear epitopes are continuous stretches of amino acids within a protein, while conformational epitopes are formed by amino acids that are brought together in the protein's folded structure.
- The immune system recognizes and binds to these epitopes, initiating an immune response, which can include the production of antibodies or the activation of T-cells.
2. Major Histocompatibility Complex (MHC):
- The Major Histocompatibility Complex (MHC) is a set of genes found in most vertebrates, including humans. It encodes the cell surface proteins known as human leukocyte antigens (HLAs) in humans.
- MHC molecules play a vital role in the immune system, specifically in presenting antigens to the immune cells. They function by binding and displaying antigenic peptides (derived from the breakdown of antigens) on the cell surface for recognition by T-cells.
- MHC molecules are of two main types: MHC class I and MHC class II. MHC class I molecules are found on almost all nucleated cells and present peptides from intracellular pathogens to cytotoxic T-cells. MHC class II molecules are mainly expressed on antigen-presenting cells (APCs) and present peptides from extracellular pathogens to helper T-cells.
In summary, antigenic epitopes are specific regions on antigens that interact with the immune system, whereas the Major Histocompatibility Complex (MHC) is a group of genes that encode proteins involved in presenting these antigenic peptides to immune cells.