BRAINCAKECell Recognition
The immune system must tell apart the body's own cells (self) from anything foreign (non-self). It does this by recognising antigens.
An antigen is a molecule, usually a protein or glycoprotein, that can trigger an immune response. Antigens are found on the surfaces of cells and viruses, and toxins can also act as antigens. Each antigen has a specific shape, so it can be recognised by receptors with a complementary shape.
Every nucleated body cell carries self antigens, including proteins of the major histocompatibility complex (MHC). The combination of MHC proteins is almost unique to each individual (except identical twins). During development, lymphocytes with receptors that bind strongly to self antigens are destroyed, so the immune system normally tolerates the body's own cells.
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Key terms in this lesson
- lymphocyte
- A type of white blood cell responsible for the specific immune response, each type recognising one particular antigen.
More in Response to Infection
- Non-specific Responses
- Fevers
- Phagocytosis
- Lymphocytes
- B cells
- T Cells
- The Humoral Response
- The Effector Stage
All 20 lessons in Response to Infection · All Edexcel A-level Biology topics