In many infection and vaccination settings, CXCR3 expression is required for T cells to enter the lung tissue.55,56 Lung entry subsequently affects CXCR3 expression in an antigen-dependent manner57 and CXCR3low cells are preferentially found in close proximity to the vasculature.57 However, both CXCR3high and CXCR3low cells can provide protection from respiratory infections.56–59 The signals required for the downregulation of CXCR3 are not entirely clear. The gene discussed is CXCR3; the disease is respiratory tract infectious disorder.