TNF/TNF-receptor signalling has been linked to reduced memory CD4+ T cell frequencies after influenza infection in mice (DeBerge et al., 2014; Singh et al., 2007), and T cells from older people have been found to be more sensitive to TNF-alpha-induced apoptosis via the extrinsic pathway (Gupta, 2002; Aggarwal et al., 1999), suggesting that TNF may impact Tfh cell expansion or survival. The gene discussed is CD4; the disease is influenza.