TNF and viral infectious disease: To determine the pulmonary chemokine and cytokine responses to secondary pneumococcal infection following H9N2 virus infection, we measured the levels of chemokines (keratinocyte chemoattractant [KC] and mouse macrophage inflammatory protein-2 [MIP-2]), the anti-inflammatory cytokine interleukin-10 (IL-10), and proinflammatory cytokines (IL-6, tumor necrosis factor alpha [TNF-α], and IL-1β) at 6 h after pneumococcal infection at 7, 14, or 28 dpi.