Many pathways lead to asthma: the importance of natural killer T cells

The pathogenesis of asthma is complex. It is associated with:

- a number of environmental factors, eg, allergens, infection, air pollution, exercise, and obesity
- multiple cell types
- several cellular and molecular pathways

These pathways include adaptive and innate immunity and involve T(H)2 cells, mast cells, basophils, eosinophils, neutrophils, airway epithelial cells, and natural killer T (NKT) cells.

Inflammation in asthma (click to enlarge the image).

NKT cells express NK cell and T lymphocytes markers. They recognize lipids in the context of CD-1.

NKT cells function in concert with T(H)2 cells or independently of adaptive immunity in causing airway hyperreactivity.

The clinical relevance of NKT cells in human asthma is supported by the observation that NKT cells are present in the lungs of some patients with asthma, particularly patients with severe, poorly controlled asthma.

NKT cells can explain some mechanisms that drive the development of asthma, particularly in the case of asthma associated with neutrophils, viral infection, and air pollution.

References:
Natural killer T cells are important in the pathogenesis of asthma: The many pathways to asthma. Umetsu DT, Dekruyff RH. J Allergy Clin Immunol. 2010 Mar 23.