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Serology Techniques

Serology techniques are procedures used by immunologists to discover antigens in blood serum or plasma. Blood serum is the portion of the blood that contains the blood cells. A person who works in a serology lab diagnostically tries to identify antibodies in the blood serum through specialized techniques. These techniques also discover a person's blood type, check for infection and check for foreign matter in the blood.

  1. Enzyme-linked Immunosorbent Assay

    • Enzyme-linked Immunosorbent Assay, called ELISA, is a biochemical serology technique that discovers an antibody in a blood sample. In an ELISA test, the antigen for the antibody being searched for is placed in wells in a microtiter plate. Then, the serum, diluted to 400-fold, is added to the wells. If the antibody is present in the serum, it will bind itself to the antigen already attached to the walls of the wells. The plate is then washed in a specific way, an antibody that is made specifically to attach to other antibodies is put into the wells, and then the plate is washed again. The bound antibodies become enzymes and are tested for chemical changes with a catalysis. The color the enzyme changes to relates to which antibody is in the blood.

    Agglutination

    • Agglutination is a process of finding which bacterial antigens are in a sample of blood serum. Due to the fast-acting process, agglutination is a largely used process in serology. The test is completed by adding the specific bacteria to a sample of blood serum. If the blood serum has the blood's antibodies that are fighting the same bacteria, the active antibody will clump both bacteria together. This technique also is used to ensure a blood transfusion is acceptable, as rejected red blood cells will clump to the antibodies in the host blood.

    Precipitation

    • A precipitation serology technique is a process where a dissolved antigen is added to a sample of blood serum in a test tube. The test tube is then added to a precipitation machine that spins it, causing centrifugal force to push any infected antibodies to the bottom of the test tube. With the clumps of active antibodies pushed to the bottom of the tube, they become small specks that are visible without the use of a microscope.

    Complement Fixation

    • In the complement fixation technique of serology, a complement protein is added to the antigen and antibody in the blood serum. This is the oldest method of serology testing and is no longer used for testing for immunity. This test is performed by adding diluted blood serum in a microtiter plate. The same antigen is added to each sample and a series of different proteins are added to discover which protein the antibody will then react to and correct the antigen.

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