Inhibition of the cytokine response does not protect against lethal H5N1 influenza infection.

Because proinflammatory cytokines are markedly elevated during H5N1 influenza virus infection, the "cytokine storm" is hypothesized to be the main cause of mortality. Here, we demonstrate that mice deficient in the hallmark inflammatory cytokines TNF-alpha, IL-6, or CC chemokine ligand 2 succumb to infection with A/Vietnam/1203/04 (H5N1) virus, as do wild-type mice treated with glucocorticoids for suppression of cytokines. Because cytokine inhibition does not protect against death, therapies that target the virus rather than cytokines may be preferable.