In order to follow the potential role of VCAM-1 in neutrophil and NK cell recruitment to PR8 infected lungs, we first verified that both leukocytes comparably expressed the main VCAM-1 binding integrin VLA-4 (α4β1) on their surface during active infection in both WT and ICAM-1/2-/- mice (Figure 3F). Here, VCAM1 is linked to infection.