Why are immune therapies offered by clinics?

For many patients experiencing fertility problems, no underlying causes are found. Due to this inability to explain why a successful pregnancy does not occur, one theory widely shared is that the cause may be the patient’s immune system.

Transplanted organs from a different individual are rejected by the recipient’s immune system unless powerful drugs are taken to suppress this immune rejection. The baby is a different individual from the patient as half its genes are inherited from the biological father. In some patients it was thought that the patient’s immune system could ‘reject’ their foetus unless their immune system was also altered and suppressed during pregnancy. However, it is now clear that immune rejection of the foetus rarely, if ever, happens.

Suppressing the immune system of a pregnant patient may expose the patient and baby to considerable risks, including life-threatening infections.

Does the patient’s immune system ever reject their baby?

If rejection of the foetus occurs a particular type of immune cell, the uterine Natural Killer (NK) cell, has been proposed as the root cause. The NK cells in the womb or uterus were given this name as they are related to NK cells circulating in our blood. Blood NK cells are essential in the early stage of viral infections when they kill infected cells.

NK cells are naturally present in the uterus but the placenta is always a physical barrier between the patient’s immune cells and their baby. Thus, despite their name, these uterine NK cells are never in contact with the foetus and do not attack the embryo. Indeed, it is now becoming clear that they are beneficial for pregnancy and work in cooperation with the placenta so it can successfully become established in the uterus.

Please refer to our separate Reproductive Immunology patient information leaflet for detailed information about the tests and treatments available at Aria.