Chlamydia pneumoniae infection modulates cytokine production by human T lymphocytes and monocytes (43.11)

Abstract

Abstract Continuous cell line cultures of human lymphocytes (MOLT-4) and monocytes (THP-1) were examined for production of immunoregulatory cytokines involved in immune responses to the intracellular opportunistic pathogen Chlamydia pneumoniae (Cp). Infection with Cp is widely prevalent and believed involved in chronic inflammatory diseases such as atherosclerosis and even neurodegenerative diseases like Alzheimer’s disease and multiple sclerosis. The results of this study showed that MOLT-4 and THP-1 cells were readily infected by Cp in vitro assessed by immunofluorescence microscopy for Cp lipopolysaccharide (LPS) and by real time RT-PCR for 16S rRNA expression. Stimulation of MOLT-4 cells with heat killed Cp (KCp) or Escherichia coli LPS (E. coli LPS) induced Th1 cytokines IFNγ and IL-12 and Th2 cytokine IL-10, but infection with viable Cp showed a dominant Th1 cytokine production. Cp infected THP-1 cells mainly produced IL-12 and enhanced TNFα and IL-10 production compared to cultures stimulated with KCp or E. coli LPS as a control. These results suggest that Cp infection modulates the immune response to a Th1 biased cytokine profile by T cells in addition to induction of TNFα by monocytes/macrophages. Such effects are likely involved in antibacterial immunity against Cp infection.