CD4 and infection: Using this technique, groups have demonstrated that CD4+, CD8+, and MAIT cells control attenuated or virulent Francisella replication in macrophages, further underscoring the importance of these cell subsets during infection (Cowley and Elkins, 2003; Cowley et al., 2005; Collazo et al., 2009; Roberts et al., 2016).