Development of a microassay for histamine release.

Area of Science:

• Immunology
• Allergy Research
• Diagnostic Assays

Background:

• Histamine release assays are crucial for diagnosing allergies.
• Conventional methods require larger blood volumes, limiting pediatric and extensive testing.
• A sensitive and reproducible assay for small blood volumes is needed.

Purpose of the Study:

• To develop and validate a microassay for measuring histamine release from human leucocytes and whole blood.
• To compare the sensitivity and reproducibility of the radioenzymatic assay (REA) with spectrofluorometry.
• To assess the assay's suitability for small blood volumes, including pediatric samples.

Main Methods:

• Development of a microassay for histamine release.
• Comparison of single isotope histamine radioenzymatic assay (REA) with spectrofluorometric assay.
• Testing assay sensitivity with diluted whole blood (thumb prick) and undiluted venous blood.
• Correlation of histamine release with skin-prick tests.

Main Results:

• The micro-histamine release assay demonstrated high sensitivity (0.2 ng/ml) and good agreement with spectrofluorometry (r=0.94).
• Excellent qualitative agreement (92%) was observed between histamine release and skin-prick tests.
• Diluted whole blood samples showed complete agreement with undiluted venous blood for histamine release responses.
• Leukocyte sensitivity to antigen remained consistent within a ten-fold dilution.

Conclusions:

• The developed micro-histamine release assay is sensitive, reproducible, and suitable for small blood volumes.
• This assay facilitates allergy testing in infants and allows for multiple allergen assessments.
• It provides a valuable tool for studying basophil sensitivity when blood availability is limited.