Proinflammatory cytokines.

Cytokines that are especially linked to the production of inflammatory processes and acute-phase responses. They include IL-1, IL-6, IL-8, TNF, and INF-γ.

Properdin.

A nonimmune gamma-globulin that can be activated to a convertase enzyme, which in turn causes activation of the alternative pathway of the complement system.

Respiratory burst.

A sudden increase in cellular respiration that occurs when phagocytes become activated. This process generates free oxygen radicals with microbicidal properties.

Self-limitation.

The waning over time of immune responses to antigenic stimulation.

Siderophores.

Iron-binding proteins secreted by bacteria that gather the iron needed for bacterial growth. Siderophores compete with mammalian iron-binding proteins for the iron they carry.

Specificity.

Property of the immune system that enables it to recognize and respond to each of the myriads of foreign, molecularly unique antigens encountered throughout an individual's lifetime.

Suppressor cell. A CD8+ T-lymphocyte that helps control (suppress) an excess production of specific immunoglobulins.

T-cells (or T-lymphocytes).

Thymus gland-dependent lymphocytes responsible for the development and maintenance of cell-mediated immunity. T-cells recognize only short peptide sequences on intracellular protein antigens expressed on cell surface membranes; T-cells may exert a helper, suppressor, or effector function.

Thymosin.

A zinc-containing hormone produced by stromal cells of the thymus gland that abets the actions of T-cells throughout the body.

Tumor necrosis factor (cachexin, lymphotoxin).

Cytokine with action closely similar to IL-1. In addition, TNF stimulates cytotoxicity by PMN and eosinophils and inhibits the activity of lipoprotein lipase.

Urticaria.

Itchy dermal wheals caused by type I hypersensitivity reactions.