• Chlamydia trachomatis;
  • infectious load;
  • immune response


The regulation of immune response and chlamydial infectious load in the cervix of human females is largely unknown. Infectious load in terms of inclusion-forming units (IFUs) was determined by quantitative cultures in Chlamydia-positive women, in asymptomatic women, women with mucopurulent cervicitis (MPC) and women with fertility disorders (FD). CD4+, CD8+, CD14+ cells, myeloid and plasmacytoid dendritic cells (mDCs and pDCs) in the cervix were quantified by flow cytometry. Cervical cytokines, levels of β-estradiol and C-reactive protein (CRP) in serum and cervical immunoglobulin A antibody to chlamydial major outer membrane protein antigen, chlamydial heat shock protein 60 and 10 antigens were measured by an enzyme-linked immunosorbent assay. In asymptomatic women, chlamydial load showed significant positive correlations with CD4, mDCs, interleukin-12 (IL-12) and IL-2; however, negative correlations were found with CD8 and IL-8 levels. In women with MPC, chlamydial IFUs correlated positively with CD8, pDC number, IL-8, CRP and interferon-γ (IFN-γ). In women with FD, chlamydial load showed a significant positive correlation with the pDC number, IL-10 and estradiol level and a negative correlation with CD4 and IFN-γ. Overall, these results suggest that the interplay between chlamydial infectious load and host immune responses may be the deciding factor for the clinical condition presented during Chlamydia trachomatis infection.