CD4 and infection: Upregulation of CTLA‐4 in TREG cells and CD4+ T cells has previously been shown in human (Goncalves‐Lopes et al, 2016; Mackroth et al, 2016) and mouse malaria infection models (Haque et al, 2010; Hafalla et al, 2012), and its expression has been associated with restricting pathogenic cellular responses during acute infection, at the expense of inhibiting cell proliferation (Mackroth et al, 2016) and antibody responses to infection (Kurup et al, 2017).