Glossary
The vocabulary of immunology, in plain words.
- Antigen
- Anything the adaptive immune system can recognise.
- Antibody
- A Y-shaped protein made by B cells that binds one antigen specifically. Also called immunoglobulin.
- B cell
- A lymphocyte that makes antibodies.
- T cell
- A lymphocyte that matures in the thymus. Helper T cells direct responses; cytotoxic T cells kill infected cells.
- MHC
- Major histocompatibility complex: the molecules that display protein fragments to T cells. In humans, HLA.
- Innate immunity
- Fast, non-specific defences present from birth.
- Adaptive immunity
- Slower, specific responses by B and T cells that leave memory.
- Dendritic cell
- A cell that captures antigen in the tissues and presents it to T cells.
- Macrophage
- A large phagocyte that engulfs microbes and debris.
- Cytokine
- A small signalling protein by which immune cells talk to one another.
- Complement
- A cascade of blood proteins that marks and punctures microbes.
- Inflammation
- The local response to injury or infection: heat, redness, swelling, pain.
- Clonal expansion
- The multiplication of the few lymphocytes that recognise an antigen.
- Memory cell
- A long-lived lymphocyte left after a response.
- Tolerance
- The state of not responding to a particular antigen, above all the body’s own.
- Regulatory T cell
- A T cell that suppresses other immune cells.
- Autoimmunity
- An immune response against the body’s own tissues.
- Adjuvant
- A vaccine ingredient that strengthens the response to the antigen.
- Monoclonal antibody
- Identical antibodies from a single cell line, all binding the same target.
- Checkpoint
- A molecular brake on T cells. Blocking it can release a response against a tumour.