Early responses of primary human and bovine monocytes, monocytic THP-1 cells and THP-1 cell-derived macrophages to vital Toxoplasma gondii tachyzoites

INTRODUCTION: Different innate immune cell types are known to release extracellular traps (ETs) in response to invasive pathogens, including parasites. These ETs function to trap, immobilize, and eventually kill pathogens. In line with this, monocytes and macrophages have been shown to release ETs, known as monocyte/macrophage extracellular traps (METs). Toxoplasma gondii (T. gondii) is an apicomplexan zoonotic parasite that infects humans and homeothermic animals. While most studies have focused on prolonged exposure of immune cells to T. gondii, this study characterized the early innate immune reaction of mononuclear phagocytes to vital T. gondii tachyzoites. METHODS: Primary human and bovine monocytes, monocytic THP-1 cells, and THP-1 cell-derived macrophages (M0-, M1-, and M2-like) were exposed to T. gondii tachyzoites for 4 h. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), immunofluorescencemicroscopy, and confocal microscopy were used to visualize cell activation and the presence of METs. Additionally, the release of pro-inflammatory cytokines interleukin (IL)-1

• Hanke, D.
• Velásquez, Z. D.
• Büttner, K.
• Krueger, A.
• Ross, R.
• Hecker, A.
• Mazurek, S.
• Grau, V.
• Taubert, A.
• Hermosilla, C.
• Richter, K.
• Conejeros, I.