Inducible endothelial ICOSLG expression has been described, particularly after inflammatory stimulation (Khayyamian et al. 2002; Klingenberg et al. 2005), and regulates CD4+ (Khayyamian et al. 2002) and CD8+ T-lymphocyte functionality during cardiac allograft rejection (Klingenberg et al. 2005), suggesting that inflammatory-induced endothelial ICOSLG expression could activate and shape the local immune reaction at the site of injury or infection. Here, CD4 is linked to infection.