In experimental infection studies of adults, increased levels of CD4+ T-cell-derived IFN-γ, IL-2, IL-4, IL-10, and TNF-α and the number of CD8+IFN-γ+ T cells correlated with increased disease severity and hospitalization, emphasizing the potential immunopathogenic role of CD4+ T cells during RSV infection [257]. Here, TNF is linked to infection.