complement fixation

fixation /fix·a·tion/ (fik-sa´shun)

1. the process of holding, suturing, or fastening in a fixed position.

2. the condition of being held in a fixed position.

3. in psychiatry: (a) arrest of development at a particular stage, or (b) a close suffocating attachment to another person, especially a childhood figure, such as a parent.

4. the use of a fixative to preserve histological or cytological specimens.

5. in chemistry, the process whereby a substance is removed from the gaseous or solution phase and localized.

6. in ophthalmology, direction of the gaze so that the visual image of the object falls on the fovea centralis.

7. in film processing, removal of all undeveloped salts of the film emulsion, leaving only the developed silver to form a permanent image.

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complement fixation , fixation of complement addition of another serum containing an antibody and the corresponding antigen to a hemolytic serum, making the complement incapable of producing hemolysis.

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complement fixation

n.

The binding of active complement to a specific antigen-antibody pair used in diagnostic tests, such as the Wasserman test, to detect the presence of a specific antigen or antibody.

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complement fixation,

an immunologic reaction in which an antigen combines with an antibody and its complement, causing the complement factor to become inactive or fixed. The complement-fixation reaction can be tested in the laboratory by exposing the patient's serum to antigen, complement, and specially sensitized red blood cells. Complement-fixation tests can be used to detect antibodies for infectious diseases, especially syphilis and viral illnesses. They are rarely used in clinical practice today. See also anticomplement, complement, immune system, immunity, Wassermann blood test.

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complement fixation,

n an immune reaction in which an antigen-antibody complex inactivates or fixes the complement of the antibody. Complement fixation tests are used to determine antibodies for infectious diseases, such as syphilis and certain viral infections.

Complement fixation.

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complement (kom´plment),

n one of 11 complex, enzymatic serum proteins. In an antigen-antibody reaction, complement causes lysis. Complement is also involved in anaphylaxis and phagocytosis.

complement fixation,

n an immunologic reaction in which an antigen combines with an antibody and its complement, causing the complement factor to become inactive, or “fixed.”

complement-fixation test (C-F test),

n a serologic test in which complement fixation is detected, indicating the presence of a particular antigen. The Wassermann test for syphilis is a C-F test, used to detect amebiasis, Rocky Mountain spotted fever, try-panosomiasis, and typhus.