KLRK1 and asthma: After allergen challenge in patients with allergic asthma, granzyme B expressing NK cells and granzyme B protein are elevated in the airways.41,42 Furthermore, the NKG2D ligands MICA and ULBP-2, which can be cleaved from the cell surface and detected in soluble forms in the serum if produced in sufficient quantities, are elevated in the serum of children with HDM allergy.32,64 Based upon our findings, any factors that promote NK-cell activity would be predicted to worsen inflammation in asthma.