Serum complement C4

C4 is a beta globulin synthesized in tissues such as liver, lymphoid tissue, bone marrow, peritoneal macrophages, and monocytes. C4 is involved in the classical activation pathway of complement. Increased C4 levels are seen in the acute phase of rheumatic fever, nodular arteritis, dermatomyositis, myocardial infarction, Reiter syndrome, and various types of arthritis; reduction in autoimmune slow-lived liver, SLE, multiple Sexual sclerosis, rheumatoid arthritis, kidney disease, subacute sclerosing whole encephalitis, etc. In SLE, the decrease in C4 is often earlier than other complement components and is later than other components. Lupus nephritis is significantly lower than non-lupus nephritis C4 values. Basic Information Specialist classification: cardiovascular examination classification: blood examination Applicable gender: whether men and women apply fasting: fasting Tips: Do not eat too greasy, high-protein foods the day before the blood draw, avoid heavy drinking. The alcohol content in the blood directly affects the test results. After 8 pm on the day before the medical examination, fasting should be done to avoid affecting the detection of indicators such as blood glucose in the second sky. Normal value 130 to 370 mg/L. Clinical significance Increased C4 levels are seen in the acute phase of rheumatic fever, nodular arteritis, dermatomyositis, myocardial infarction, Reiter syndrome, and various types of arthritis; reduction in autoimmune slow-lived liver, SLE, multiple Sexual sclerosis, rheumatoid arthritis, kidney disease, subacute sclerosing whole encephalitis, etc. In SLE, the decrease in C4 is often earlier than other complement components and is later than other components. Lupus nephritis is significantly lower than non-lupus nephritis C4 values. High results may be diseases: children with subacute thyroiditis, viral hepatitis, chronic renal failure precautions (1) The ratio of antigen to antibody should be appropriate. If the antigen is too concentrated, a conical spike cannot be obtained, and the antibody is too concentrated to make the precipitation peak too low, which affects the sensitivity of the test. (2) Electrophoresis immediately after loading, and the specimen should not be too much to prevent the peak shape from widening. (3) C4 is not very stable. It can increase the C4 value by about 36% when stored at 4 °C for 2 weeks or at -20 °C for 60 days. It is relatively stable within 1 week. Inspection process (1) Preparation of antibody agarose plate: The melted 10.0 g/L agarose gel was mixed with an appropriate concentration of anti-C4 serum, and poured (8 cm × 8.5 cm), and the cells were perforated after cooling and solidification. (2) 8 holes were punched at 1 cm from one side, the hole diameter was 3 mm, the hole pitch was 5 mm, and the agarose in the hole was picked. (3) A 1:4 dilution of the test serum and 10 μl of different concentrations of C4 reference serum were added to each well. The three-layer filter paper was used as a bridge, and electrophoresis was carried out in an electrophoresis tank of 0.025 mol/L pH 8.6 barbital buffer. One end of the hole was connected to the cathode, the terminal voltage was 3 to 4 V/cm, and after electrophoresis for 4 to 5 hours, the power was turned off. , take off the agar plate measurement. Not suitable for the crowd There are no special taboos. Adverse reactions and risks No relevant information.