Major histocompatibility complex
Major Histocompatibility Complex (MHC)
The Major Histocompatibility Complex (MHC) is a set of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances. MHC proteins are found in all higher vertebrates. In human beings, the complex is also called the HLA (human leukocyte antigen) system.
Pronunciation
Major Histocompatibility Complex: /ˈmeɪdʒər ˌhɪstəkəmˈpætɪbɪlɪti kəmˈplɛks/
Etymology
The term "Major Histocompatibility Complex" is derived from the words "major" (meaning large or important), "histo-" (from the Greek 'histos' meaning tissue), "compatibility" (from the Latin 'compatibilis' meaning suitable), and "complex" (from the Latin 'complexus' meaning entwined or complicated).
Function
MHC molecules bind to peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T-cells. This process is crucial for immune system function.
Classes of MHC
There are two main types of MHC class molecules:
- MHC Class I molecules: These are found on all nucleated cells and are essential for the immune system to recognize infected cells.
- MHC Class II molecules: These are found on professional antigen-presenting cells (like macrophages, dendritic cells, and B cells) and are essential for the immune system to recognize exogenous pathogens.
Related Terms
- Antigen: A substance that triggers an immune response, especially the production of antibodies.
- T-cells: A type of white blood cell that is of key importance to the immune system and is at the core of adaptive immunity.
- Immune System: A complex network of cells, tissues, organs, and the substances they make that helps the body fight infections and other diseases.
- Pathogen: A bacterium, virus, or other microorganism that can cause disease.
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