We co-cultured BMDC with Ag-specific CD4+ T cells isolated specifically from day 12 post infection from Cm or mock infected mice as it is well established that the CD4+ T cells are (1), the primary source of Ag-specific IFN-γ production [27]; (2), CD4+ T cells are the most important effector cell population that have the potential to provide protective responses against a subsequent infection [9] and; (3), adaptive immune responses are initiated around days 12-15 post infection in a well characterized 27-33 day murine genital infection model [7, 10]. Here, CD4 is linked to infection.