Additional reagents for determination of acute infections

IgG absorption

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

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 solution, avidity buffer 1

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 or more) by urea treatment.
The following reagents for avidity determination are available: