Additional Reagents for the Determination of Acute Infections
- Before a patient's serum is tested for specific antibodies of the IgM class, antibodies of class IgG must be removed, for example by immunoabsorption.
- Specifically bound IgG would displace IgM from the antigen leading to false IgM negative test results.
- Moreover, the absorption prevents any IgM class rheumatoid factors present from reacting with specifically bound IgG and thus leading to false IgM positive test results.
- Indication: an IgG absorption of serum samples should always be performed for all IgM antibody determinations in infectious serology before incubating the sera.
- IgG/RF absorbent is contained in the sample buffer in all ELISAs for infectious serology (class IgM).
EUROSORB IgG/RF Absorbent for indirect immunofluorescence
- Functional principle: the EUROSORB reagent contains an anti-human IgG antibody preparation from goat. Immunoglobulin G of a serum or plasma sample is bound with high specificity by these antibodies and precipitated. If the sample also contains rheumatoid factors, these will be absorbed by the anti-human IgG/IgG complex.
- Incubation time of the sample with the reagent is 15 minutes.
- All IgG subclasses are bound and precipitated by the anti-human IgG antibodies.
- Human serum IgG in concentrations of up to 15 mg/ml and rheumatoid factors are completely removed by the absorbent (average serum IgG concentration in adults: 12 mg/ml).
- The recovery rate of the IgM fraction is almost 100%.
- One unit contains 4.5 ml absorbent, sufficient for the absorption of 100 serum samples.
Urea Solutions and Avidity Buffers for the Determination of Low-Avidity Antibodies in Infectious Serology
- To identify low-avidity antibodies in a patient’s serum, two immunofluorescence tests are performed in parallel: one test is carried out in the conventional way, the other one includes urea treatment between incubations with patient’s serum and peroxidase-labelled anti-human IgG, resulting in the detachment of low-avidity antibodies from the antigens.
- Low-avidity antibodies are present if the fluorescence intensity is significantly reduced (two intensity levels ore more) by urea treatment.
- The following reagents for avidity determination are available:
IFT, Ab against
urea solution, 5 M
urea solution, 6 M
urea solution, 8 M
urea solution, 8 M
avidity buffer 1
avidity buffer 2