CD4 and infection: In the i.n. model, infection by vΔ169 caused enhanced production of several cytokines (IL-2, IL-6 and TNF-α) and chemokines (CCL11, CXCL9 and CXCL10) within 1 day p.i. (Fig 11) and subsequent greater recruitment of macrophages and CD4+ and CD8+ T cells (Fig 12) and increased lung weight (Fig 11D).