Comparison of IgE values as determined by different solid phase radioimmunoassay methods

Area of Science:

• Immunology
• Clinical Chemistry

Background:

• Accurate quantification of immunoglobulin E (IgE) is crucial for diagnosing and monitoring various allergic and immunological conditions.
• Measuring low IgE concentrations presents significant technical challenges, impacting diagnostic accuracy.
• Existing radioimmunoassay methods, including direct sandwich and inhibition techniques, vary in their reliability at low concentrations.

Purpose of the Study:

• To compare the accuracy of a direct sandwich radioimmunoassay (PRIST) with three inhibition radioimmunoassay methods for quantifying low IgE concentrations.
• To evaluate the performance of these methods in measuring IgE levels in cord serum samples.

Main Methods:

• Radioimmunoassay techniques were employed, specifically a direct sandwich method (PRIST) and three inhibition methods.
• The methods were compared for their ability to measure IgE concentrations, particularly in the low range (1-50 U/ml).
• IgE levels in cord serum samples from healthy individuals were quantified using the evaluated methods.

Main Results:

• All methods showed good correlation for IgE values above 50 U/ml.
• Inhibition methods tended to produce falsely elevated values for IgE concentrations below 50 U/ml.
• The direct sandwich test (PRIST) demonstrated the best correlation for very low concentrations (1-10 U/ml), especially when using a correction factor for non-specific serum effects.
• Mean IgE values in cord serum were 0.4 U/ml for PRIST and 0.6 U/ml for the corrected inhibition test.

Conclusions:

• The direct sandwich assay (PRIST) is more reliable for accurately measuring low IgE concentrations compared to inhibition methods.
• Inhibition methods may overestimate IgE levels at lower concentrations.
• The PRIST method is recommended for its simplicity and accuracy in quantifying low IgE levels, as demonstrated in cord serum analysis.