Neutrophil granulocytes: tour guides of T cells

What actually happens with flu? Well, in short: the influenza virus (and here I ask between a real, caused by the influenza virus flu and the common cold Infe kt caused by coronaviruses or Ade novir s , Various cheiden!)usually reaches our respiratory tract through a droplet infection and infiltrates there into the lung epithelial cells. The multiplication of viruses makes us sick (up to 20,000 can be formed per cell) because the cell dies in the process. In addition, of course, there is our immune response to fight the virus-infected cells. And this is exactly where the so-called cytotoxic T cells, or CD8 + T cells, play a very important role. Because they are the ones who recognize the infected cells and then specifically kill them.

To do this, however, the T cells have to come to the scene and this is exactly where neutrophil granulocytes, or neutrophils for short, help. These special immune cells belong to the so-called innate immune system and represent a so-called “rapid reaction force”, which are the first to be on the spot. Lim et al. from the University of Rochester (New York, USA) was able to visualize for the first time in animal experiments what and how exactly the whole thing works. To do this, they used immunofluorescence microscopes, which can be used to color-code cells and tissues previously stained with special antibodies. The team was able to show that the neutrophils are essential to direct the CD8 + T cells to the focus of infection.
On day three or four they are already on site and during your hike (also called migration) lay out molecular breadcrumbs, which are then followed by the CD8 + T cells (see picture below), so that they arrive after about a week. These breadcrumbs consist of the Chemokin CXCL12, which is embedded in the membrane of the epithelial cells. And that is exactly the amazing thing, given the fact that the chemokines are simply secreted and the T cells follow this chemical gradient. If these neutrophils are missing or if there is no CXCL12, fewer CD8 + T cells are on site, which are also less effective.

Our immune system is just a miracle.

Neutrophil pathway directs virus-specific CD8 + T cell migration (Kihong Lim et al. Science 2015; 349: aaa4352)

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