Scientists finally have proof of mysterious immune cell in humans
As you work, each cell in the human body, Scientists discovered an elusive type of immune cell that first arises in the womb. The existence of such cells in humans has been hotly debated – until now.
These mysterious cells, known as B-1 cells, were first discovered in mice in the 1980s, according to a 2018 review in The Journal of Immunology. These cells arise early in mouse development, in the womb, and they produce different ones antibody when activated. Some of these antibodies attach to the mouse’s own cells and help clear dying and dead cells from the body. Activated B-1 cells also make antibodies that serve as the first line of defense against pathogens such as viruses and viruses bacteria.
After discovering B-1 cells in mice, a research group reported in 2011 that they had found equivalent cells in humans, but these results have not been accepted as conclusive evidence. “There was a back-and-forth at the time… Not all of them matched our profile of human B-1 cells,” says Dr. Thomas Rothstein, professor and founding chair of the Department of Investigative Medicine and director of the Center for Immunobiology at Western Michigan University, who was the senior author of this earlier work.
Now a new study published in the journal on Thursday (May 12). Scienceprovides solid evidence that B-1 cells arise early in human development, within the first and second trimester. “It validates and expands on the work we previously published,” Rothstein, who was not involved in the new research, told Live Science.
“I think this is the most conclusive data yet” supporting the idea that humans carry B-1 cells, said Dr. Nicole Baumgarth, a professor at the UC Davis Center for Immunology and Infectious Diseases, who was not involved in the new study. In theory, these cells could play a crucial role in early development, and studying them further may help scientists better understand what healthy immune system development looks like in humans, Baumgarth told Live Science.
Related: Why do we develop lifelong immunity to some diseases but not others?
A rare look at the developing immune system
The new research was published alongside three other studies recently conducted by the Human Cell Atlas (HCA) consortium, an international research group working to determine the location, function and properties of every cell type in the human body. Collectively, the four studies, all published May 12 in Science, involve analyzes of more than 1 million human cells representing more than 500 different cell types taken from more than 30 different tissues.
“You can think of it as a ‘Google Maps’ of the human body, and it’s really this ‘road map view’ of each cell and where they are located in the tissue that we are targeting,” said the study’s lead author Sarah Teichmann. Head of Cellular Genetics at the Wellcome Sanger Institute in England and Co-Chair of the Human Cell Atlas Organizing Committee.
While working on this atlas of the human body, Teichmann and her colleagues recently focused on immune Cells and particularly the immune cells that arise during early human development. Through this work, they discovered evidence of human B-1 cells. “What we show is that they do exist in humans,” Teichmann said during a May 10 news conference.
The analyzes included cells from nine developing tissues, such as the thymus, a gland that produces immune cells and hormones, and the embryonic yolk sac, a small structure that nourishes the embryo early pregnancy. All of the tissue samples analyzed by the team came from the Human Developmental Biology Resource, a tissue bank in the UK that stores human embryonic and fetal tissue, with the written permission of the donors. They also included publicly available data from previous HCA studies.
Overall, the data covered an early phase of development, ranging from four to 17 weeks after conception, ie within the first and second trimester.
Related: How ‘Spider-Man’ and ‘Pac-Man’ immune cells work together to fight off invasive bacteria
The researchers took high-resolution snapshots of these tissues at a scale of 0.001 inch (50 microns), which is thinner than a human hair, Teichmann said during the press conference. And at the single-cell level, the team analyzed all “RNA Transcripts” in each tissue that reflect the different proteins that each cell makes. Using these transcripts, the researchers were able to make inferences about the identity and function of each cell.
Through this detailed analysis, the team discovered cells that matched the description of B-1 cells found in mice, both in terms of their properties and when they appeared.
“In the mouse system, the B-1 cells arise early — they arise first,” Rothstein said. Another type of immune cell, aptly named B-2, then arises after the first B-1 cells and eventually becomes the most abundant form of B cell in the mouse. The new study suggests something similar happens in humans, where B-1 cells originate and are most abundant in early development, Rothstein told Live Science.
What purpose might these special cells serve in a developing human? They might help form new tissue as they form, Teichmann said.
“In general, when you think about fetal development, there’s massive tissue remodeling going on all the time,” Baumgarth said. For example, humans initially develop a webbing between their fingers, but this webbing is trimmed back before birth. It may be that B-1 cells help guide such tissue pruning during development, but “that’s speculation on my part,” she said.
In addition to tissue shaping, the B-1 cells could provide some level of immune protection against pathogens small enough to cross the placental barrier, Baumgarth said. Again, this is speculation, she said.
The new study advances our understanding of how B-1 cells initially develop and could lay the groundwork for future studies of how the cells function later in life, Rothstein said.
Originally published on Live Science.
Scientists finally have proof of mysterious immune cell in humans Source link Scientists finally have proof of mysterious immune cell in humans
