Every person born on Earth carries a small number of cells that originated from their mother. Roughly one in every million cells in the body may be maternal, meaning we each contain millions of cells that are genetically different from our own. Despite this, the immune system generally accepts them rather than attacking them as foreign.
Researchers have now discovered the reason. During pregnancy, a small number of the mother’s immune cells pass through the placenta and help train the developing fetus’s immune system to recognize and tolerate maternal cells. This early exposure can allow those cells to remain in the body peacefully for decades.
The Lifelong Exchange of Cells Between Mother and Fetus
Microchimerism is a long-known process in which cells are exchanged between mother and fetus, with both retaining each other’s cells.
The presence of these long-lasting foreign cells presents an interesting challenge to immunology, since the immune system is generally expected to identify and attack cells that it recognizes as foreign.
To investigate how these maternal cells can persist without triggering an immune response, a research team led by pediatric infectious disease specialist Sing Sing Way at Cincinnati Children’s Hospital Medical Center examined how maternal cells influence immune regulation and contribute to the development of the fetus’s immune system.
Researchers Investigate Maternal Microchimerism in Mice
To investigate this further, the scientists examined maternal microchimerism in mice. Building on earlier research, they bred mice whose immune cells were genetically modified to carry specific surface markers. This enabled the researchers to selectively remove these cells and determine whether immune tolerance would continue.
The findings were particularly interesting.A small group of maternal immune cells persisted after birth and was linked to regulatory T cells that help control immune responses.
To verify their findings, the researchers selectively removed the identified maternal cells from the offspring mice. The results were striking: regulatory T cells were lost, and the offspring also lost their immune tolerance toward maternal cells.
Lifelong Immune Tolerance Depends on Maternal Microchimeric Cells
The findings suggest that long-term immune tolerance to maternal microchimeric cells may rely on a very small population of maternal cells. When these cells are removed, the balance of the immune system may be disrupted. Immune tolerance requires continuous regulation throughout life.
The study could clarify microchimerism’s role in autoimmune diseases, cancer, and neurological disorders.
Microchimerism is becoming increasingly associated with a wide range of health conditions. The study helps determine whether these rare cells cause disease or support natural healing.
Read the original article on: sciencealert
