An agent produced in plants and bacteria, normally very damaging to cells.
Prominent oval masses of lymphoid tissues on either side of the throat.
A family of proteins important for first-line immune defenses against microbes.
A state of immune nonresponsiveness to a particular antigen or group of antigens.
A group of similar cells joined to perform the same function.
Complex protein molecule on the surfaces of T cells that recognizes bits of foreign antigen bound to self-MHC molecules.
A small white blood cell that recognizes antigen fragments bound to cell surfaces by specialized antibody-like receptors. “T” stands for the thymus gland, where T cells develop and acquire their receptors.
An immature cell from which other cells derive. Bone marrow is rich in the kind of stem cells that become specialized blood cells.
A lymphoid organ in the abdominal cavity that is an important center for immune system activities.
The clear liquid that separates from the blood when it is allowed to clot. This fluid contains the antibodies that were present in the whole blood.