Coxiella burnetii-infected NK cells release infectious bacteria by degranulation

Matthiesen, Svea GND; Zaeck, Luca Mirko GND; Franzke, Kati GND; Jahnke, Rico; Fricke, Charlie; Mauermeir, Michael; Finke, Stefan GND; Lührmann, Anja; Knittler, Michael R. GND

Natural killer (NK) cells are critically involved in the early immune response against various intracellular pathogens, including Coxiella (C.) burnetii and Chlamydia (C.) psittaci. Chlamydia-infected NK cells functionally mature, induce cellular immunity, and protect themselves by killing the bacteria in secreted granules. Here, we report that infected NK cells do not allow intracellular multi-day growth of Coxiella, as is usually observed in other host cell types. C. burnetii-infected NK cells display maturation and IFN-γ secretion, as well as the release of Coxiella-containing lytic granules. Thus, NK cells possess a potent program to restrain and expel different types of invading bacteria via degranulation. Strikingly though, in contrast to Chlamydia, expulsed Coxiella largely retain their infectivity and, hence, escape the cell-autonomous self-defense mechanism in NK cells.



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Matthiesen, Svea / Zaeck, Luca / Franzke, Kati / et al: Coxiella burnetii-infected NK cells release infectious bacteria by degranulation. 2020.


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