This test is used to find out the antibodies that are not attached to the surface of the blood and freely floating in the bloodstream. Antibodies are the protective proteins produced by the immune system and also known as immunoglobulins. Antibodies are produced when any foreign substance or virus or bacteria enters into the body. These foreign substances are known as antigens. So, antibodies released by the immune system recognizes and attaches to the antigens in order to remove them from the body. Whenever foreign substances enter the body they bind to the surface of B lymphocytes and stimulates the B cells to divide and mature into a group of identical cells called as a clone. The matured B cells called as plasma cells secrete millions of antibodies into the bloodstream and lymphatic system. The circulating antibodies attack and eliminate the antigens that are similar to the one that stimulates the immune response. So, antibodies bind to the antigens and neutralize its toxin by changing antigens chemical composition are known as antitoxins. Some antibodies cause antigen lysis or can attract the microbe-killing scavenger cells to eat the antigens are known as phagocytes. Antibody production continues until all the antigens were eliminated and removed from the body. These antibodies remain in blood circulation for several months to provide more immunity against the particular antigen. Antibodies are in Y shaped and have two large heavy chains and two small light chains. It consists of the constant and variable region. It has Fc region at the bottom of Y. This Fc region is the part of the antibody which attaches to the antigen. Depending on the Fc region, the antibodies are of five (5) subtypes. They are IgG, IgM, IgA, IgD, IgE. IgG provides long-term protection as it presents in the circulation for long period after the presence of an antigen. IgM is involved in the ABO blood group antigens on the red blood cells (RBC’s) surface. IgM also enhances the ingestion of cells by phagocytosis. IgA is also the first defense for intestine, lungs, and nose. They bind antigens to the microbes before they invade tissues and keeps antigens in secretion and when secretion is expelled, antigens are also expelled. IgD helps in the induction of antibody production and presents on the surface of B-cells. IgE binds to the basophils and mast cells. If an individual is suffering from autoimmune disorder then the body’s immune system attacks own healthy cells or organs. In this case, the immune system recognizes own healthy cells as foreign substances and start producing antibodies. These antibodies attack the healthy cells and cause severe damage to the health of the individual. The doctor may ask to perform this test if an individual is suffering from symptoms like the dark color of urine, increased heart rate, enlarged liver and spleen, lightheadedness, dizziness, inability to do physical activity, yellowing of the skin, paleness of the skin, fever. In some cases, this test is performed to find out the effectiveness of the treatment. If a patient is treated for hemolytic anemia by blood transfusions, blood, and marrow stem cell transplant then the doctor may ask to perform this test to evaluate the IgG levels in the body. This helps the doctor to rule out the patient disease condition. This test is also done to know whether an individual is having hemolytic anemia, to detect Rh IgG antibodies in serum. It is also used for screening and detection of unexpected antibodies in the serum. This test helps to find whether a pregnant woman has antibodies in the blood that could pass to an unborn baby and can cause harm to it. Indirect Coomb's test is used to find out the antibodies in the blood of receiver before getting a blood transfusion that would react badly to the donated blood. If the test results are negative then there are no antibodies in the blood and one can safely get blood from the donor. If test results are negative for pregnant women, then no need to worry about the unborn baby as there are no antibodies in pregnant women to harm the unborn baby. In case the test results are positive then there are antibodies in the blood and one can not receive the donor's blood as it may lead to clump the blood. If the test results are positive for pregnant women, then there are antibodies in the body and can transport to the unborn baby body and may cause hemolytic anemia in the unborn baby. So, one should get more tests to finalize the diagnosis. ### Precautions: Some drugs or medications may change the levels of IgG in the blood. So inform your doctor prior to the test if you are on any medications or recently gets a surgery.
Also known as: ICT Blood, Indirect Coombs Test, Coombs Indirect Test.