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http://www.rialab.com/miscarriages_prevented.phpBlocking AntibodiesEarly in pregnancy, the mother's immune system receives signals from the tiny fetus. Many of the signals are hormonal, but others come directly from genetic messages that the father has contributed. Some of the messages involve the tissue type, also known as the human leukocyte antigens (HLA) and the white blood cell (leukocyte) type. HLA are expressed on white blood cells. They are unique to each individual and allow the body to identify anything foreign to it such as infections, cancers, transplanted organs and fetuses.
One half of the fetus's HLA type is contributed by mother and the other half by father. When a woman becomes pregnant, her body's immune system usually recognizes the father's HLA as different from her own, and the white blood cells in her uterus produce protective, blocking antibodies. These antibodies coat the baby's cells and protect the fetus from mother's killer cells. If father's HLA is too similar to mother's, her cells may not recognize differences that are vital to the production of blocking antibodies.
Women who have successful pregnancies and have no history of miscarriages normally, have high levels of blocking antibodies even in the nonpregnant state vs women who miscarry and whose levels tend to be low even when pregnant.
Through HLA tissue typing we can identify couples who look too much "alike". In addition we can measure the ability of a couple's cells to respond to each other i.e. level of blocking antibodies, using sophisticated equipment which combine computers and lasers (cell flow cytometry).
Treatment for Blocking AntibodiesTwo treatments have been offered for low blocking antibody levels: paternal white cell immunizations and IVIg. Immunizing the mother with concentrates of the father's white blood cells amplifies the HLA signal. Approximately 50% of patients have a discernible increase in the blocking antibody level after 2 treatments. The other 50% require additional white cell immunizations. To determine if additional preparations will be required, the blocking antibody level should be measured 3 to 4 weeks after the second and all subsequent immunizations. When blocking levels are elevated, prior to conception, the rate of successful pregnancy is nearly 80%.
The risk associated with white blood cell immunization is the possible transmission of infectious agents that the father's blood may be harboring. This can be avoided by testing his blood for any significant infections. Very uncommonly, there can be a local skin infection caused by bacteria on mother's own skin. This is easily treated.
IVIg is an alternative to white cell preparations. The doses vary between 10 and 60 grams per month. Some doctors have had success with the lower doses of IVIg (10 grams) for patients who have only the blocking antibody problem. The blocking antibody levels should be measured monthly to determine the need for future infusion.
The main differences between white cell transfusion and IVIg are that IVIg has rapid onset of action and is more versatile. However, it is more expensive and provides temporary blocking. In multiple studies, the success rate is the same provided that the blocking antibody levels are adequate.
