Swedish researchers have discovered the importance of the thymus in pregnant women. This small organ ensures that the immune system works against infections and at the same time it guarantees the tolerance of the fetus by the mother, while it is a foreign body.
Pregnancy still has some secrets that scientists are discovering little by little. Researchers from linkoping university in Sweden have discovered the role of the thymus, an organ of the immune system, normally not very functional in adults, and which would intervene in the tolerance of the fetus by the immune system of the pregnant woman, without there being immunosuppression.
Their results are presented in the journal Journal of Allergy and Clinical Immunology.
Protect the mother without rejecting the fetus
The thymus is a small organ located near the heart. It produces T cells, distributed throughout the body, which will determine immune reactions: a foreign body, a bacterium or a virus for example, must be fought by the immune system.
The reaction of the latter during pregnancy is a source of questions for scientists: how the body can both protect the mother from infections without rejecting the fetus, 50% of which comes from the father’s cells and which is therefore a foreign body immunologically?
Greater production of regulatory T cells
Previous studies have shown that in mice, the thymus has a reduced role during pregnancy: it produces fewer T cells, which prevents the body from rejecting the fetus. Swedish scientists wanted to understand if the same phenomenon occurs in humans. They analyzed the blood of 86 women, 56 of whom were pregnant. The level of regulatory T lymphocytes (Treg), a type of T cells, was analyzed because they are the ones that control the other cells of the immune system.
“We have shown that the production of T cells by the thymus does not vary during pregnancy, explains Sandra Hellberg, one of the authors of this study. We have also shown that the production of regulatory T cells, which can weaken the response immune, tends to increase during pregnancy.” These cells would guarantee the protection of the mother against viruses and bacteria while they also ensure the tolerance of the fetus.
Ways to better understand multiple sclerosis
These results answer old questions from the scientific community, but they also provide insights into the understanding of certain autoimmune diseases such as multiple sclerosis. The thymus of those affected has reduced activity and produces fewer T cells, and pregnant women with multiple sclerosis generally experience fewer symptoms during pregnancy.
Swedish researchers now want to continue their research on pregnant women with multiple sclerosis to understand the exact role of T cells in improving or worsening symptoms.
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