Immunity system complexity: how dendritic cells act (Introduction)

by David Turell , Tuesday, July 18, 2023, 14:32 (284 days ago) @ David Turell

Not like other immune cells:

https://www.sciencedaily.com/releases/2023/07/230717143221.htm

"The cells of the immune system circulate mainly in the blood and migrate into the body's tissues after an inflammation. Some types of immune cells, however, are permanently located in the tissues, where they come together to form three-dimensional networks.

"How do these networks form and how are they maintained? For the long-lived macrophages (phagocytes), the answer is already known: They settle in so-called niches. These are environments of connective tissue cells that supply the macrophages with nutrients and keep them alive.

"A team led by Professors Georg Gasteiger, Dominic Grün and Wolfgang Kastenmüller...has now turned its attention to a related type of immune cells, the so-called dendritic cells.

"These immune cells are essential for the control of immune responses because they are at the first line of defense of the immune system: They recognize foreign structures, take them in and process them into a kind of mugshot. They then present the photo to other immune cells and trigger a specific immune response, for example against pathogens or cancer cells.

"The special thing about dendritic cells: They only live for about a week and during this time they continuously migrate through the body's tissues. “In this respect, it was clear that the classic niche concept would not work here" , says Wolfgang Kastenmüller.

"The JMU team found a completely new concept for this, according to which three-dimensional cell networks can organize themselves: Dendritic cells orient themselves to the blood vessels and migrate one after the other along their outer wall – similar to children walking in single file. The blood vessels thus determine the three-dimensional arrangement of the cells.

***

"As the JMU team reports in the journal Immunity, it is due to a locally acting cytokine, the FLT3 ligand, that the dendritic cells always stay close together during their developmental migration.

"The cytokines are continuously and evenly produced locally and consumed by the dendritic cells. If there are gaps in the group, more cytokines are available for the isolated dendritic cells. This surplus speeds them up in their development and movement and helps them to reconnect with the group. When the cells have moved up, they have a little less cytokines available again due to competition from their neighbours. Accordingly, they slow down their developmental speed.

***

"The JMU researchers’ data so far is based on the analysis of lymph nodes from animal models. The team next wants to test whether the same principles of network organisation of dendritic cells apply to all tissues and also in humans."

Comment: from our knowledge of evolution, if a system works in one application, it will be used everywhere. This is another example of immune complexity design.