Normal Natural Killer Cell Level Found in COPD Patients

Results suggest the cells not as abundant in obstructive diseases as previously thought

WEDNESDAY, April 4 (HealthDay News) -- Natural killer T cells represent a minority of the CD4+ bronchoalveolar cells in patients with asthma and chronic obstructive pulmonary disease (COPD), and are present at levels seen in healthy subjects, according to study findings published in the April 5 issue of the New England Journal of Medicine.

To address conflicting reports regarding the abundance of invariant natural killer T cells in patients with pulmonary diseases, Pandurangan Vijayanand, M.D., of Southampton General Hospital in Southampton, U.K., and colleagues used flow cytometry and real-time polymerase chain reaction (RT-PCR) to measure the levels of these cells in patients with mild or moderately severe asthma, COPD, and in healthy control subjects.

Invariant natural killer T cells were found to represent 2 percent of the total population of CD4+ T cells in bronchoalveolar lavage, sputum and airway biopsy samples taken from all subjects. The investigators found no significant differences between patient and healthy control samples and RT-PCR analyses for invariant natural killer T-cell-receptor genes were negative.

"Whether or not natural killer T cells expand in numbers to the extent reported…[previously], studies in animals suggest that these cells are likely to have a role in the pathogenesis of asthma," according to Ling-Pei Ho, M.D., Ph.D., of Oxford, U.K., in an accompanying editorial. "Further work on the precise role of this potent group of immunoregulatory cells in airway inflammation is overdue."

The study authors report multiple affiliations with various pharmaceutical companies.

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