Reproductive Immunology

Definition - What does Reproductive Immunology mean?

Reproductive immunology is a specialized area of medicine that deals with detection and management of reproductive disorders that are either due to direct or indirect interactions with the immune system.

The immune system is the defense system of the body, but under abnormal circumstances, the immune system can develop immunological reactions between the immune cells and the cells of the reproductive system, such as the eggs, sperm or even a developing embryo. These immune reactions can lead to difficulty in conceiving or recurrent pregnancy losses (RPL), therefore reproductive immunology has an emerging role in the evaluation of infertility.

FertilitySmarts explains Reproductive Immunology

The immune system is the body's inner defense system that protects the internal environment against harmful invaders and is primarily made up of white blood cells and substances produced and released by them. There are certain abnormalities that can happen in the immune system that can result in an increased or decreased function of these immune cells and its constituents. Over-activity of the immune system can lead to white blood cells attacking normal cells of the body. In case of an under-active immune system, it makes the body more prone to infective disease and certain forms of cancers.

The immune system of a woman plays an important role in fertilization and implantation of the embryo. Natural killer (NK) cells are a group of specialized white blood cells that are present in large numbers in the uterus and they help in the early stages of pregnancy including implantation and formation of the placenta. Altered activity of these cells is thought to interfere with the normal process of implantation, leading to infertility. Further studies are needed on this topic.

An embryo that is growing inside a uterus is partly foreign to the mother as half of its genetic content belongs to the father. But during pregnancy, the immune system starts to recognize the embryo as a part of the body and does not try to get rid of it. This is called maternal immune tolerance. If the woman develops an abnormal immune reaction against the fetus, that can lead to a miscarriage or pregnancy complications.

The placenta is partly responsible for the maintenance of immune tolerance. The placenta allows the passage of antibodies from the mother to the fetus that protects the fetus from infections, but it blocks cells from being exchanged from the maternal side to the fetus and vice versa and prevents the development of immune reactions.

The immune system in men can sometimes produce antibodies against their own sperm cells leading to the death of loss of function of the sperm cells due to being attacked by immune cells and this leads to male factor infertility. Very rarely, women can also develop antisperm antibodies in their blood which can destroy sperm cells when they are deposited in the vagina.

Specialists in reproductive immunology are involved in the management of infertility when a cause for infertility is not found after the routine infertility investigations, or if there is a strong suspicion of an underlying immune system association.

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