CD4 and tuberculosis: The mouse model of TB has many advantages and key findings in the mouse have been replicated in man, such as critical roles for CD4+ T cells, TNF-α and IFN-γ (Flynn and Chan, 2001), but pathology in the mouse differs from human TB (Young, 2009) and humanised mice are required to generate caseating lesions (Calderon et al., 2013; Heuts et al., 2013).