Role of the basophil activation test (BASOTEST) in the diagnosis of immediate allergic reactions to betalactams

Abstract Rationale In vitro methods to diagnose immediate allergic reactions to betalactams (IARB) avoid risks. We evaluated the basophil activation test (BASOTEST) to diagnose IARB. Methods 70 patients with IARB, diagnosed with a well-validated protocol: skin tests with BPO-PLL, MDM, amoxicillin, ampicillin and the culprit drug, RAST to BPO-PLL, AXO-PLL and the culprit drug and, if negative, a provocation test. In all patients BASOTEST with BPO-PLL, MDM, benzylpenicillin, amoxicillin, ampicillin, and the culprit drug were performed. Results There were 38 women and 32 men (mean age 41.6 years). The mean interval between the reaction and study was 11.6 months, the type of reaction was anaphylaxis in 53 cases and urticaria in 32. The drugs involved were amoxicillin in 59 cases, cephalosporins in 8 and benzylpenicillin in 3. Patients were classified in three groups: A (N=53), those with skin test positive; B (N=10), skin test negative and RAST positive; C (N=7), skin test and RAST negative and provocation positive. BASOTEST was positive in 34 patients (48.6%), 27 in Group A (50.9%), 6 in Group B (60%) and 1 in Group C (14.3%). The percentages of positivity to the different haptens were: 20% to BPO-PLL, 0% to MDM, 29% to amoxicillin, 12.5% to ampicillin, 20.6% to benzylpenicillin and 75% to the culprit drug. Conclusions BASOTEST is a useful tool for the diagnosis of immediate allergic reactions to betalactams, but mainly in those patients with skin test or RAST positive. It was less sensitive in those patients diagnosed by provocation test.