TNF and influenza: revealed that TNF-α and IL-10 optimize CXCL13 expression in AMs (24); thus, it is possible that the activated CXCR2 pathway may inhibit CXCL13 expression by controlling TNF-α/IL-10 production by influenza-infected AMs, in turn limiting the positive regulation of TNF-α/IL-10 on CXCL13 production in AMs.