The existence of mysterious immune cells in humans has been proven: what they do and why they are needed

The mysterious cells, known as B-1 cells, were first discovered in mice in the 1980s. They appear early

developmental stages of the mouse, still in the womb.When activated, they produce various antibodies. Some of them attach to the mouse's own cells and help cleanse the body of those that are dying and have already died. Activated B-1 cells also produce antibodies that act as the first line of defense against pathogens such as viruses and bacteria.

Since the discovery of B-1 cells in mice in 2011the researchers reported that they had found equivalents in humans. However, the scientists' results were not accepted as definitive evidence. "Not everyone agreed with our profile of human B-1 cells," Dr. Thomas Rothstein, professor and director of the Center for Immunobiology at Western Michigan University, said in a press release. He was the senior author of this previous work.

What did the scientists find out?

Now, in a new study published inin the journal Science, scientists have provided compelling evidence that B-1 cells appear early in human development, during the first and second trimesters of pregnancy. “This confirms and expands on the work we published previously,” said Rothstein, who was not involved in the new study.

“This is compelling data.They support the idea that humans are carriers of B-1 cells,” said Dr. Nicole Baumgart, professor at the Center for Immunology and Infectious Diseases at the University of California, Davis. Theoretically, these cells may play a critical role in early development. By studying them further, scientists can learn more about what healthy immune system development looks like in humans.

A new look at the immune system

New work published along with three othersresearch recently conducted by the Human Cell Atlas consortium. This is an international group of experts that works to determine the position, function and characteristics of each cell type in the human body. Together, the four studies, published in the journal Science, include an analysis of more than 1 million human cells. All of them belong to 500 different types and are taken from 30 different fabrics.

"You can think of it as 'Google Maps'of the human body, and they are really “street maps” with individual cells and their location in tissues that we are aiming for,” said Sarah Teichmann, senior author of the study. Head of Cell Genetics at the Wellcome Sanger Institute in England and Co-Chair of the Steering Committee of the Human Cell Atlas.

Helping to compile this atlas of the human body,scientists focused on immune cells. In particular, those that arise in the course of early human development. It was through this work that they discovered evidence for the existence of human B-1 cells.

What are they needed for?

These cells help form new tissues as they form, the scientists say.

When the fetus develops, there is constantlymassive tissue remodeling. For example, humans initially form a webbing between their fingers, but it is "cut off" before birth. It's possible that B-1 cells help guide this cutting of tissue during development, suggested Nicole Baumgart, who was not involved in the study.

According to her, in addition to tissue formationB-1 cells can provide some level of immune protection against pathogens small enough to cross the placental barrier. But this is also just a guess. This remains to be seen.

The new work expands our understanding of how B-1 cells initially develop and could lay the groundwork for future research into how cells function later in life.

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