Role of NKp46+ natural killer cells in house dust mite-driven asthma

House dust mite (HDM)-allergic asthma is driven by T helper 2 (Th2) lymphocytes, but also innate immune cells control key aspects of the disease. The precise function of innate natural killer (NK) cells during the initiation and propagation of asthma has been very confusing, in part because different, not entirely specific, strategies were used to target these cells. We show that HDM inhalation rapidly led to the accumulation of NK cells in the lung-draining lymph nodes and of activated CD69+ NK cells in the bronchoalveolar lumen. However, genetically engineered Ncr1-DTA or Ncr1-DTR mice that constitutively or temporarily lack NK cells, still developed all key features of acute or chronic HDM-driven asthma, such as bronchial hyperreactivity, Th2 cytokine production, eosinophilia, mucus overproduction, and Th2-dependent immunoglobulin serum titers. The same results were obtained by administration of conventional NK1.1 or asialo-GM1 NK cell-depleting antibodies, antibody-mediated blocking of the NKG2D receptor, or genetic NKG2D deficiency. Thus, although NK cells accumulate in allergen-challenged lungs, our findings comprehensively demonstrate that these cells are not required for HDM-driven asthma in the mouse.

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