As dual cytokine-producing T cells have been shown in general to be functionally superior over single cytokine-producing cells (23) and correlated with protection against chlamydia in murine models (24), we examined the CD4+ T cells from women who had positive CD4+IFN-γ responses for their ability to co-produce TNF-α or IL-2. This evidence concerns the gene CD4 and chlamydia trachomatis infectious disease.