*3.6. NK Cells*

Natural Killer (NK) cells are cells of the innate immune system that serve to target and eliminate tumors and cells infected by viruses [19]. There have been conflicting reports on how exactly NK cells modulate allergic lung inflammation, where some have reported that NK cells play an inhibitory role, and others report that NK cells promote allergen-induced inflammation [19]. One study reported the role of prostacyclin signaling in NK cell function in allergic airway inflammation and found that IP KO mice had reduced allergic lung inflammation induced by house dust mites and decreased Th2 cytokine production [19]. While this finding is in contrast to data previously mentioned in this review, in this model, IP KO mice had a greater number of pulmonary NK cells than WT mice. Depleting NK cells restored allergic inflammation in the IP KO mice to levels seen in WT mice, and transferring NK cells into airways suppressed allergic inflammation [19]. Thus, this leads to the speculation that IP signaling promotes NK cell function to regulate allergies.
