Complement fixation test (CFT)

The complement fixation test (CFT) is an assay using an immunohemolytic mechanism as an indicator system to detect antigens or antibodies of another reaction system. As early as 1906, Wasermann applied it to the diagnosis of syphilis, the famous Fahrenheit reaction. This traditional experiment has been continuously improved, in addition to the diagnosis and epidemiological investigation of infectious diseases, and is also used in the detection and analysis of some autoantibodies, tumor-associated and HLA. Basic Information Specialist classification: Infectious disease examination and classification: immunological examination Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: Normal value, negative, ie 0 to 1:10. Positive: The complement fixation test can be applied in the following aspects: 1 diagnosis of infectious diseases. Detection of pathogenic antigens and corresponding antibodies. 2 detection of other antigens. For example, tumor-associated antigens, protein identification in blood, HLA typing, and the like. 3 autoantibody detection. The result was more than 1:10 positive, and the coincidence rate of diagnosis of brucellosis was 97.96%. Tips: Try to eat less and eat as much as possible, and arrange your diet reasonably. Normal value The normal value is 0 to 1:10. Clinical significance The complement fixation test can be applied to the following aspects of the diagnosis of infectious diseases. Detection of pathogenic antigens and corresponding antibodies. 2 detection of other antigens. For example, tumor-associated antigens, protein identification in blood, HLA typing, and the like. 3 autoantibody detection. The result was more than 1:10 positive, and the coincidence rate of diagnosis of brucellosis was 97.96%. Precautions Complement binding test involves many components in the reaction, complex influencing factors, complicated operation steps and strict requirements. A slight oversight will lead to incorrect results, so it has been replaced by other more acceptable methods in various assays. . Inspection process (1) Titration of blood: 1 Take 1ml of complement, add 9ml of BBS, and then dilute to 1:20, 1:30, 1:40, 1:50, 1:60, 1:80, 1:100, 1:200, 1:400, and take 50 0.2 ml of hemolysin, add 9.8 ml of BBS, which is 1:100 hemolysin, and then continue to dilute to 1:800, 1:1600, 1:3200, 1:6400. 2 Take the square array of test tubes, longitudinally add 0.1ml of different concentrations of complement, and add 0.1ml of hemolysin in each row (all should be added from the highest dilution), then add BBS0.2ml, complement and The hemolysin control tubes were each added with BBS 0.3 ml, and finally 2% sheep red blood cells were added to each tube. The total amount of each tube was 0.5 ml, shaken, placed in a 37 ° C water tank for 30 min, and the results were observed. The highest dilution of complete hemolyzed complement and hemolysin is the respective unit. In practical applications, hemolysin is used in 2U (3200÷2=1600) and complement is used in 2.5U (80÷2.5=32). (2) Formal test: 1 Operate with a V-type microplate, and make a test well for each specimen. A serum control well. BBS0.025ml was added to each well. 2 Dip serum (0.025 ml) with a dilution stick to the first well, rotate and transfer to the second well for a total of eight wells, thus obtaining a 1:2 to 1:256 dilution. 3 Add each reagent according to Table 2: An example of a complement binding assay for measuring antibodies by a small amount is described. According to Table 14-6, various reagents were gradually added. After incubation, the various control tubes should be observed first, which should be consistent with the expected results. Negative and positive control tubes should be clearly hemolyzed and non-hemolyzed; antibody or antigen control tubes, serum control tubes to be tested, and control tubes of positive and negative controls should be completely hemolyzed. Spontaneous hemolysis should not occur in sheep red blood cell control tubes. The complement control tube should show 2U for total dissolution, 1U for total dissolution with a little red blood cells, and 0.5U should be insoluble. For example, the complete dissolution of the 0.5U complement control indicates that the amount of complement is excessive; if the 2U control tube does not show hemolysis, indicating that the amount of complement is insufficient, the results are affected, and the test should be repeated. The results of the complement fixation test showed that the test serum was not hemolyzed and the hemolysis was negative. Not suitable for the crowd There are no taboos. Adverse reactions and risks There are no related complications and hazards.