Glossary of mast cell related terms: F-L

FceRI: the high affinity IgE receptor; where IgE molecules bind to the outside of cells, like mast cells; binding the FceRI receptor triggers mast cell activation

Food associated, exercise induced anaphylaxis: An IgE mediated reaction that is triggered by ingesting certain foods in close time proximity to exercise

Food protein induced enterocolitis syndrome (FPIES): An allergic reaction to food proteins that is not mediated by IgE, usually found in infants; the most severe non-IgE mediated food hypersensitivity

Gastroparesis: a condition in which stomach contents are not emptied into the small intestine within an appropriate time period without an obvious anatomical explanation

Granule: a pocket inside a cell that holds molecules to be released outside of the cell

Granulocyte: white blood cells that have granules inside the cells that hold molecules to be released outside of the cell; mast cells, eosinophils, basophils and neutrophils are granulocytes

H1: histamine 1 receptor

H1 inverse agonist: a class of drugs that interferes with the effect of histamine at the H1 receptor

H2: histamine 2 receptor

H2 blocker: a class of drugs that interferes with the effect of histamine at the H2 receptor

Heparin: a mast cell mediator; a blood thinner

Hepatomegaly: swelling of the liver

Hepatosplenomegaly: swelling of the liver and spleen

Hereditary angioedema (HAE): a heritable blood disorder that causes episodes of protracted swelling that can be life threatening.

Histamine: a neurotransmitter; responsible for a large portion of symptoms seen in mast cell disease and anaphylaxis

HPA axis: the signals and feedback loops that regulate the activities of the hypothalamus, pituitary gland and adrenal glands to coordinate the body’s stress response; also helps regulate digestion, immune activation, sexuality and energy metabolism

Hypersensitivity: allergic reaction

Hypersplenism: overactivity of the spleen

IgE: an antibody that triggers allergic responses

Kounis Syndrome: an event in which a patient experiences severe chest pain or heart attack as the result of an allergic reaction; also called allergic angina or allergic myocardial infarction

Late onset anaphylaxis: Anaphylaxis that begins several hours after exposure to trigger

Leukotrienes: Structural class related to prostaglandins produced by the enzyme 5-lipoxygenase (5-LO); mediators released by mast cells.

Leukotriene receptor antagonist: A class of drugs that interferes with the function of leukotrienes; examples include montelukast and zafirlukast.

Ligand: a molecule that binds to another molecule, triggering a specific effect; with regards to mast cell disease, ligands bind to receptors, such as IgE (ligand) binding to FceRI (receptor)

LO: lipoxygenase; the enzyme that produces leukotrienes

Low histamine diet: a diet which minimizes dietary sources of histamine, which can help reduce symptoms for some mast cell patients; there is no authoritative list of low histamine foods and some trial and error is required