ASTHMA/ALLERGY

A rapid, relatively strong, inflammatory response to antigen (immediate hypersensitivity) is called atopy or an allergic reaction. A severe systemic reaction to antigen, called anaphylaxis, can be life threatening resulting in cardiovascular collapse.

The inflammatory response can occur within the skin or at the mucus membranes. If this inflammatory response to antigen occurs in the lung producing a reversible airway obstruction, bronchial hyperresponsiveness, and the accumulation of eosinophils, the phenotype is called asthma.

The cells that are involved in these reactions include:

1. B-cells: produce IgE,
2. T-cells [Th-2 cells]: produce cytokines that include Il-3, Il-4, Il-5, Il-13,
3. mast cells/basophils: bind IgE and release mediators of the inflammatory reaction (histamine) as well as cytokines ( GM-CSF, Ll-3, Il-4, and Il-5), and
4. eosinophils: release leukotrienes, reactive oxygen products, and protein granules.

Other cells such as macrophages and dendritic cells may act as antigen presenting cells; and local epithelial cells are a source for proinflammatory mediators including cytokines, chemokines and nitric oxide.

Genetically, in various human populations, the asthma phenotype has been linked to 11 chromosomal regions: 5p15, 5q23-31, 6p21.3-23, 11p15, 12q14-24.2, 13q21.3, 14q11.2-13, 17p11.1, 17q11.2, 19q13, and 21q21.

Cellular interactions

Summary table