Killer T Cells May Trigger Asthma

A new study shows that invariant natural killer T cells play a prominent pathogenic role in human asthma, suggesting that therapy should target these cells.

Researchers examined the bronchial fluid of 44 adult patients, 14 of whom had moderate- to-severe asthma with frequent wheezing, coughing, and shortness of breath. Six other patients were healthy, while five others had sarcoidosis, a different type of respiratory inflammatory disease. The researchers found that 63% of the cells found in asthma patients were killer T cells, compared to less than 1% of the cells in the fluid from either controls or patients with sarcoidosis. The natural killer T cells expressed an invariant T cell receptor and produced type 2 helper cytokines. The study was published in the March 16, 2006, issue of the New England Journal of Medicine.

Since invariant natural killer T cells make up only 0.1% of circulating white blood cells, they were easy to miss and only recently have techniques been available to isolate them, said Dale T. Umetsu, an immunologist at Children's Hospital Boston (MA, USA) and Harvard Medical School (also in Boston), who conducted the study along with researchers from Stanford University (California, USA), Karolinska Institute (Stockholm, Sweden), and the La Jolla Institute for Allergy and Immunology (San Diego, CA, USA). If invariant natural killer T cells do indeed play a prominent pathogenic role in human asthma, therapies for asthma that target pulmonary invariant natural killer T cells may be highly effective, the researchers concluded.

Natural killer T cells are part of the immune system, fighting infections, and in instances, preventing some autoimmune diseases. When a person develops too many of the cells, or if the cells get activated inappropriately, inflammatory agents are released that can lead to such illnesses as colitis or heart disease. Natural killer T cells are sensitive to lipid, essentially fat that is found in the body and in some plants and food.



Related Links:
Children's Hospital Boston