Scarsi Mirko, Bosio Carla, Coccoli Silvia, Barucco Amilcare, Tavelli Giovanna, Airò Paolo
Rheumatology and Clinical Immunology Unit, Spedali Civili and University of Brescia, piazzale Spedali Civili, 1, 25123, Brescia, Italy.
Clin Rheumatol. 2014 Jun;33(6):873-5. doi: 10.1007/s10067-014-2605-3. Epub 2014 Apr 13.
A strong association between the human leucocyte antigen (HLA)-B58:01 allele and allopurinol-associated severe cutaneous adverse reactions (SCAR) has been reported. A screening for HLA-B58:01 before allopurinol has been suggested in guidelines for management of gout. HLA-B58:01 screening is generally based on molecular biology methods that may be not suitable for wide application. We have retrospectively evaluated the performance on a rapid flow cytometry (FCM) test, based on the use of a monoclonal antibody specific for HLA-B17, an antigen that can be split into HLA-B57 and -B58 alleles by molecular biology testing, which is used to screen for HLA-B57:01 before prescription of the antiretroviral agent abacavir in HIV-positive patients. Among 475 samples that were analysed by FCM and by molecular biology test as gold standard, 2 out of 89 false negative tests for HLA-B58:01 were found. The sensitivity was 97.8% and the negative predictive value was 98.9%. We have shown that a FCM test can identify almost all HLA-B58:01 positive individuals. As FCM laboratories are more widely available than molecular biology ones, this approach could be used to reduce the risk for allopurinol-induced SCAR. Where both facilities are available, a two-step strategy (FCM as screening, molecular biology for confirmation) may reduce the cost of the screening.
