CD4 and chlamydia trachomatis infectious disease: Our prior study on adaptive T cell responses in peripheral blood mononuclear cells (PBMCs) from women treated for chlamydia found a significantly higher frequency of C. trachomatis-specific CD4, but not CD8, IFN-γ responses in women without reinfection5; however, C. trachomatis antigens used were optimum for inducing CD4 T cell responses, likely skewing responses to CD4 T cells and limiting evaluation of CD8 T cell responses.