An indirect immunofluorescence assay is an antibody that binds to an antibody (herein referred to as a primary antibody) that binds to an antigen, and uses an antibody corresponding to the primary antibody (ie, an anti-antibody) (herein referred to as a secondary antibody, secondary antibody). The fluorescein molecule coupled to it was incubated with the cells and observed under a fluorescence microscope.

Basic Information

Specialist classification: Infectious disease examination and classification: immunological examination

Applicable gender: whether men and women apply fasting: not fasting

Tips: Do not eat too greasy, high-protein foods the day before the blood draw, avoid heavy drinking. Normal value


Clinical significance

Abnormal results:

A single serum titer of ≥1:64 or a double-fold increase in serum titer or the presence of IgM antibodies can be diagnosed as rickettsial infection. This method does not distinguish between types of rickettsia infected by patients. The presence of specific IgM antibodies against rickettsia suggests a recent infection.

People who need to be tested:

Congenital toxoplasma infection, endemic typhus, fever, pediatric mycoplasma pneumonia, brucellosis, etc.


Before inspection:

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.

When checking:

Should relax, avoid the contraction of blood vessels caused by fear, increase the difficulty of blood collection.

Inspection process

1. Add 0.01 mol/L, pH 7.4 PBS to the specimen to be tested, and discard it after 10 minutes to keep the specimen at a certain humidity.

2. Add the appropriately diluted fluorescently labeled antibody solution to cover the specimen completely, and place it in a covered enamel box for a certain period of time (reference: 30 min).

3. Remove the slide and place it on the slide holder. Rinse with 0.01 mol/L, pH 7.4 PBS, then soak in PBS three-cylinder with 0.01 mol/L, pH 7.4, 3-5 min per cylinder. , from time to time oscillate.

4. Remove the slide and use a filter paper to remove excess water, but do not dry the specimen, add a drop of buffered glycerin, and cover with a coverslip.

5. Immediately observe with a fluorescence microscope. Observe the specific fluorescence intensity of the specimen, which can generally be expressed by "+":

(-) no fluorescence; (±) very weak suspicious fluorescence; (+) fluorescence is weak, but clearly visible; (++) fluorescent bright; (+++--++++) fluorescent shining. The specific fluorescence intensity of the specimen to be tested is "++" or more, and the various controls are (±) or (-), which can be judged as positive.

Not suitable for the crowd

There are no taboos.

Adverse reactions and risks

There are no related complications and hazards.