The Opposite Effects of DNA and Protein Components of Listeria Monocytogenes and Toxoplasma gondii on Immunologic Characteristics of Dendritic Cells

The innate immune system utilizes pattern recognition receptors (PRRs) to recognize microbes. Pathogens contain various molecules with diverse effects on immune response. In this study, we evaluated the effect of DNA and protein components derived from two intracellular microorganisms including Listeria monocytogenes (L.monocytogenes) and Toxoplasma gondii (T. gondii) on dendritic cells (DCs) activation and ensuing adaptive immune responses. DNA and protein components of L. monocytogenes and T. gondii were prepared using relevant kits. DNA and protein components of these two pathogens were added to immature DCs (iDCs). Subsequently, co-stimulatory expression and cytokine production by DCs were measured. Finally, we evaluated the stimulatory capacity of mature DCs (mDCs) in DC-T cells co-culture. The results showed that protein matured-DCs produced higher level of IL (Interleukin)-12p70. There was also a significant increase in Interferon-Gamma (IFN-γ) production and proliferative capacity in T cells co-cultured with protein matured-DCs. On the other hand, DNA matured-DCs produced significantly higher amounts of Transforming growth factor-beta (TGF-β). Collectively, these results imply a regulatory nature for DNA and potent stimulatory character for protein components of these two intracellular microorganisms.