In normal maternal serum, there is a specific IgG antibody against spousal lymphocytes, which is produced by human leukocyte antigens, trophoblast and lymphocyte cross-reacting antigens that stimulate the maternal immune response. Such antibodies can inhibit the lymphocyte response, close the cytotoxic effect of maternal lymphocytes on the embryonic trophectoderm, prevent the recognition of fetal antigens by helper T lymphocytes, and prevent the maternal immune system from attacking the embryo, and close the production of macrophage movement inhibitory factor by lymphocytes stimulated by the same antigen, hence the name closed antibody (APLA). Chao Lan, Infertility Treatment Center, Qilu Hospital, Shandong University
Studies have shown that the mother can produce allergenic T cells during pregnancy, which can destroy embryonic cells, but the killing function of allergenic T cells can be inhibited by confining antibodies. However, about 80-90% of women with recurrent miscarriages do not detect such specific confinement antibodies, so there are unsuppressed cytotoxic cells in the body that can act directly on the embryo or indirectly damage the fetus or placenta by releasing inflammatory mediators, resulting in miscarriage. Repeat miscarriage is associated with maternal APLA deficiency, and the greater the number of miscarriages, the greater the likelihood of maternal APLA deficiency, which can lead to strong maternal rejection of the fetus, recurrent spontaneous miscarriage in early pregnancy, and hypertensive disorders of pregnancy, intrauterine growth restriction, and even intrauterine fetal death in late pregnancy. Therefore, it is essential to test for APLA in patients with recurrent miscarriage.
For patients who are negative for closed antibodies, immunotherapy with peripheral blood lymphocytes from the spouse is currently available to increase the level of closed antibodies in the patient. The treatment is usually given once in 21 days for a course of 3 sessions.