IFNG and chlamydia trachomatis infectious disease: The presence of antibodies in cervical secretions of women correlates with lower bacterial shedding,5 and interferon (IFN)-γ-positive responses in peripheral blood mononuclear cells (PBMCs) stimulated with cHsp60 correlates with a decreased risk of acquiring a subsequent chlamydial infection.6 Studies in mice consistently identify a key protective role for CD4+ Th1 cells and the cytokine IFN-γ.7, 8, 9 The protective role of antibodies is more multifaceted and ranges from direct bacterial neutralization10 to accelerating CMI through Fc-mediated uptake in antigen-presenting cells.11