After demonstrating that proteolytic processing of TNF-α by CD8+ T cells was required for alveolar epithelial cell production of CXCL2 in vitro, we next examined whether proteolytic processing of TNF-α on the surface of activated CD8+ T cells was required for CD8+ T-cell-mediated lung injury in vivo in a non-infectious transgenic mouse model of influenza infection. Here, CXCL2 is linked to influenza.