Exam 3 Review:  Chapter 21:  Immune Regulatory Molecules

histamine - A physiologically active amine, C₅H₉N₃, released from mast cells as part of the inflammatory process or in certain allergic reactions; it stimulates gastric acid secretion and causes dilation of capillaries, constriction of bronchial smooth muscle, and decreased blood pressure; it is derived from the amino acid histidine.

kinins - A group of local hormones and immune regulatory substances with a peptide structure which are released by a variety of cells including lymphocytes which cause dilation of blood vessels and affect capillary permeability; e.g., cytokinin, bradykinin.

prostaglandins - A chemical class of local hormones and immune regulatory substances which are lipids, specifically unsaturated fatty acids derived from arachidonic acid, which are involved in the contraction of smooth muscle, the control of inflammation and body temperature, and many other physiological functions.

leukotrienes - A chemical class of local hormones and immune regulatory substances, related to prostaglandins and derived from arachidonic acid, which are produced by white blood cells in an immune response to antigens, and which contributes to allergic asthma and inflammatory reactions; they have potent actions on many tissues, including the CNS, GI tract, and immune system.

costimulator - Any set of local hormones and immune regulatory substances which cooperate to regulate a particular immune response, e.g., the set of cytokines, interleukins, etc., which are released during the initial maturation of lymphocytes or during the activation (proliferation and differentiation) of B and T lymphocyte clones after antigen-presentation by a macrophage or dendritic cell.

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