Reaction pattern to histamine and codeine in a human intradermal skin test model

Area of Science:

• Allergy and Immunology
• Dermatology
• Clinical Diagnostics

Background:

• Skin prick and intradermal skin tests (IDT) are crucial for diagnosing IgE-mediated allergic disorders.
• Current literature shows significant variations in IDT techniques and result interpretation.
• Lack of standardized procedures hinders comparability between studies and clinical reports.

Purpose of the Study:

• To analyze intradermal skin test (IDT) conditions to enhance comparability across diverse study protocols.
• To establish standardized methods for more reliable allergy testing.

Main Methods:

• 24 healthy volunteers were tested on the upper back, upper arm, and forearm with varying concentrations of histamine and codeine.
• Digital imaging and NIH Image J software were used to measure weal area for precise result analysis.
• The effect of ethylene diamine tetra-acetic acid on weal size was also evaluated.

Main Results:

• Weal size demonstrated a dose-dependent response to both histamine and codeine.
• Weal areas were larger on the upper back compared to the forearm and upper arm.
• Histamine induced more consistent weal sizes than codeine, and ethylene diamine tetra-acetic acid had no significant effect.

Conclusions:

• The developed technique and findings offer valuable tools for routine clinical practice and inter-study comparisons of intradermal tests (IDT).
• Recommends using 1 mg/mL codeine and 0.1 mg/mL histamine for assessing mast-cell releasability and vascular reactivity.
• Future research should investigate local factors and opiate receptor density in mast cells influencing skin reactivity.