IL4 and infection: Our results are similar to those reported by Dutry et al., where it was observed that human macrophages activated with IL-4 were more susceptible to infection with highly pathogenic avian influenza virus (H5N1) compared to IFN-γ activated macrophages, but at later time points post-infection no differences were detected in the viral titers of culture supernatants of the two macrophage subsets [20].