CD4 and viral infectious disease: These are professional APC, triggering antibody responses by the presentation of pathogen derived peptides via the MHC-II pathway to CD4+ T cells and activating CD8+ cytotoxic T-cells (CTL) by cross-presentation of HIV-1 antigens. Since macrophages secrete cytokines that recruit T lymphocytes to sites of infection. They can “support” establishment of viral infection by enlarging the number of primary target cells (Ackerman & Cresswell, 2004). An infected macrophage can infect at least one T cell every six hours for many weeks (Groot et al., 2008).