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Gamma globulin is a class of protein found in blood plasma. There are different types of gamma globulins, but the most important are immunoglobulins — also called antibodies — which help to both prevent and fight infections and disease. Abnormal amounts of proteins in this class can be bad for a person's health or can indicate a disease. In medicine, immunoglobulin injections made from donated human blood are used to treat certain conditions, especially those that weaken the immune system.
Conditions that Affect Gamma Globulins
Levels of gamma globulin are measured through a laboratory test called serum protein electrophoresis (SPEP). Since antibodies are used to fight bacteria and viruses, an unusually high amount, or hypergammaglobulinemia, is often a sign of infection. It can also indicate liver problems, like chronic liver disease and cirrhosis, or autoimmune diseases, such as lupus and rheumatoid arthritis. Low levels of gamma globulin, or hypogammaglobulinemia, typically mean that a person has some sort of immune disorder or deficiency, such as common variable immunodeficiency (CVID).
A proliferation of abnormal gamma globulin, or paraproteins, is also a sign of immune malfunction. The abnormalities in themselves may not be harmful, but may indicate a serious immune condition, severe infection, or could progress to a dangerous condition, such as nerve damage or plasma cell cancer. They can also be caused by diseases of the gamma globulin, called gammopathies.
Treating Immune System Diseases
Immunoglobulin (Ig) can be removed from the blood of healthy donors and given to patients whose immune systems are unable to produce the necessary antibodies to effectively fight disease. Ig injections are created by combining the gamma globulins from blood donors who have already recovered from a particular disease, meaning that their blood contains the appropriate antibodies needed. This can create a temporary immunity for someone who has been exposed to a disease but who has not yet been immunized against it.
Ig injections were once given as a temporary boost to the immune system, particularly after exposure to diseases like chicken pox, measles, or hepatitis A. Vaccines have been developed for these diseases, however, so these injections are not as common as they once were. Injections may still be given to patients who do not produce enough antibodies on their own as the result of a genetic disorder or an acquired condition, however.
There are a variety of applications for these injections in order to boost the body's immune system. They can help to decrease the effects of more severe diseases and to prevent the body's immune system from destroying its own tissues, as is found in some diseases, like idiopathic thrombocytopenia purpura. It can be particularly helpful for those with genetic conditions that prevent them from producing their own antibodies. In addition, some cancer treatments also prevent the production of antibodies in patients, so Ig injections can be essential.
Treating Rh Sensitization
Some pregnant women also rely on these injections to counteract Rh sensitization. If the mother's blood is Rh- and her fetus is Rh+, it is possible that the blood types can mix during childbirth, or during an abortion, injury, or miscarriage. The mixing causes the production of antibodies by the mother's immune system that can attack the Rh+ blood cells of future fetuses. To prevent this, the woman can receive an Rh gamma globulin injection both during the pregnancy and after childbirth.