Cytochrome P450 3A activity in mothers and their neonates as determined by plasma 4β-hydroxycholesterol

International audienc

RADIOIMMUNOASSAYS EMPLOYING IMMUNOSORBENTS

ABSTRACT The use of a reaction between compounds in a two phase system – a solid phase and a liquid phase – has simplified the technical procedure of the radioimmunoassays. Antigens or antibodies can be coupled covalently to insoluble polymers to form stable conjugates with retention of immunological binding capacity. Such immunosorbents can be used in radioimmunoassays in many different ways and with the solid phase in different forms. Some of these techniques seem to be universally applicable for the assay of antigens or antibodies. In one of these, antigens or antibodies are chemically coupled to cyanogen bromide activated insoluble polysaccharides in a particle form. This method which has several advantages when compared with most other radioimmunological methods is discussed in particular. Finally, a detailed description of the preparation of an immunosorbent and its use in such a radioimmunoassay system is given.</jats:p

A RAST Neutralization Test for Detection of Blocking Antibodies in Serum after Hyposensitization

The RAST, originally developed for the assay of reaginic IgE antibodies, was applied for the detection of blocking antibodies. Sera taken ante- or post-hyposensitization were incubated with solid phase coupled allergen which neutralized reaginic IgE antibodies in the serum. The remaining activity of the reaginic IgE antibodies was measured by the RAST. When blocking antibodies were present in the serum they competed with the reaginic IgE antibodies and the amount of reaginic antibodies that was neutralized by the solid phase coupled allergen was decreased. The blocking antibodies were found in the IgG fraction of the serum taken post-hyposensitization. Blocking antibodies to various allergens were detected in 25 out of 26 tests on sera taken post-hyposensitization. The results were compared with those of Prausnitz-Küstner neutralization tests and/or patient self-neutralization tests. There was no correlation between &lt;i&gt;semi-quantitative &lt;/i&gt;results of these &lt;i&gt;in vivo&lt;/i&gt; tests and those of the RAST neutralization tests. However, cases with subjectively a strong improvement had a significantly higher mean value for RAST neutralization index than those with subjectively a weak improvement. The method is suggested as a supplement to clinical tests for evaluation of hyposensitization treatments.</jats:p