CD4 and viral infectious disease: According to what has been assumed to be the hallmark of a protective CD4+ T-cell response in various models of human viral infections [28, 34, 35], we found a significantly higher proportion of multifunctional IFN-γ+ IL-2+ TNF-α+ CD4+ T cells in subjects with LTBI, which are able to control Mtb replication compared with those with current TB disease, in which CD4+ T cells secreting TNF alone dominated the Mtb-specific response.