Aminopenicillin-associated exanthem: lymphocyte transformation testing revisited

Area of Science:

• Allergy and Immunology
• Pharmacology
• Dermatology

Background:

• Lymphocyte transformation test (LTT) is an in-vitro method for diagnosing drug hypersensitivity.
• Accurate sensitivity and specificity determination requires well-defined patient cohorts and controls.
• Ampicillin (AMP) hypersensitivity diagnosis often involves complex clinical evaluations.

Purpose of the Study:

• To prospectively assess the diagnostic utility of LTT in a clearly defined patient group.
• To compare standard and modified LTT protocols for ampicillin hypersensitivity.
• To evaluate LTT against established allergy testing methods.

Main Methods:

• Patients with ampicillin-induced exanthems were studied.
• Delayed-onset allergic ampicillin hypersensitivity was confirmed or excluded using skin and provocation tests.
• Two LTT methods were employed: standard and modified with anti-CD3/anti-CD28 stimulation.

Main Results:

• Allergic ampicillin hypersensitivity was diagnosed in 11 patients and ruled out in 26.
• Modified LTT showed higher sensitivity (72.7%) than standard LTT (54.5%).
• Specificity decreased with the modified LTT (76.9%) compared to standard LTT (92.3%).

Conclusions:

• LTT demonstrates limited diagnostic value for ampicillin-associated exanthems compared to routine allergy testing.
• Provocation testing is the definitive method for diagnosing ampicillin hypersensitivity.
• Delayed reading of skin tests is crucial for accurate interpretation and avoiding false positives.