Immunity system complexity: red cells are a part of it (Introduction)

by David Turell @, Thursday, October 21, 2021, 16:13 (890 days ago) @ David Turell

New discovery:

https://www.science.org/content/article/red-blood-cells-may-be-immune-sentinels?utm_cam...

"According to new findings that would dramatically expand their roles, red blood cells snare suspect DNA from microbial invaders or damaged tissue and warn the immune system of danger.

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"In a 2018 study, Mangalmurti’s team found a clue. The researchers determined that red blood cells harbor a type of molecular sensor, known as toll-like receptor 9 (TLR9), that recognizes and sticks to DNA molecules containing pairs of the nucleotide bases cytosine and guanine. Damaged human cells release such DNA, and the DNA of bacteria and other pathogens is also rich with these cytosine-guanine duos, or CpG motifs. They incite a strong immune system reaction that researchers ascribed primarily to white blood cells, which also sport TLR9.

"But Mangalmurti and colleagues’ latest research, published this week in Science Translational Medicine, suggests red cells take part as well. In the test tube, the researchers traced what happens when human red cells latch onto CpG-containing DNA. Small amounts of the DNA didn’t appear to affect the cells, but larger amounts caused them to scrunch up, suggesting they were responding to the stimulus.

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“'We can now say that red blood cells have an immune function” in humans and other mammals, Mangalmurti says. Most of the time, she suggests, the cells serve as janitors for normal cleanup duties, sweeping up potentially harmful DNA that leaks into the circulation from the many body cells that die every day. But during an infection or after an injury, this DNA may flood the bloodstream. The red blood cells then sacrifice themselves by encouraging macrophages to eat them, alert the immune system, and trigger inflammation. If macrophages consume too many red blood cells, however, anemia may result."

Comment: Ever more complexity in the design. Not by chance.


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