There is evidence of mysterious cells in the human immune system

While working to map every cell in the human body, scientists discovered an elusive type of immune cell that first appeared in the womb.

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 antibodies when activated. Some of these antibodies attach to the cells of the mouse and help remove dead cells from the body. Activated B-1 cells also produce antibodies that act as a first line of defense against pathogens, such as viruses and bacteria.

Researchers have published evidence for human B-1 cells.

After discovering B-1 cells in mice, a research team reported in 2011 that they had found equivalent cells in humans, but these results were not accepted. Dr. Thomas Rothstein, professor and founding chair of the Department of Investigative Medicine and director of the Center for Immunobiology at the Homer Stryker MD School of Medicine at Western Michigan University, USA, was the lead author of the earlier work. .

Now, a new study, published May 12 in the journal Science, provides solid evidence that B-1 cells emerge during early human development.

'I think this is the most convincing data' to support the idea that humans carry B-1 cells, said Dr Nicole Baumgarth, professor at the UC Davis Center for Immunology and Infectious Diseases. .

The new study is published alongside three others recently conducted by the Human Cell Atlas (HCA), an international research group working to define the location, function and characteristics of all types of cell membranes. cells in the human body. Together, the four studies - all published May 12 in the journal Science - include the analysis of more than 1 million human cells, representing more than 500 distinct cell types sampled from more than 30 different tissues.

To help build this atlas of the human body, Teichmann and her colleagues recently focused their efforts on immune cells and, in particular, immune cells that emerge during early development. of human. Through this work, they discovered evidence of human B-1 cells. "What we've shown is that they actually exist in the human body," Teichmann told a press conference May 10.

In general, the data refer to an early developmental period between 4 and 17 weeks after fertilization.

What purpose could these particular cells serve in a developing person? Teichmann says they can help create new tissues as they form.

Baumgarth says: 'When you think about fetal development, in general, there is always a massive remodeling of tissues. For example, humans initially develop a mesh between their fingers, but this membrane is trimmed back before birth. It is possible that B-1 cells help direct the pruning of such tissues during development."

In addition, B-1 cells may provide some degree of immune protection against pathogens that are small enough to cross the placental barrier.