Retrovirus Study Suggests Asociation Between Lower Body weight or Body Mass & Abacavir Hypersensitivity Reaction

About 3-5% of people receiving Abacavir in studies have developed hypersensitivity reaction to abacavir. This study's goal was to try & identify potential predisposing factors or immunological mechanisms. Esterbrook & colleagues from King's College Hospital in London and Glaxo Wellcome used an unmatched case-control study. Cases were patients who received abacavir as part of GW abacavir studies in Europe and who developed hypersensitivity (HSR) . Control patients were comprised of two groups: patients from King's College abacavir studies who did not develop hypersensitivity (group 1) and patients from King's College who started abacavir 6 months previously (group 2).

The program abstract reported HSR in 32 cases and median time to onset of symtoms was 11 days. The most common symptoms were rash (66%; grade 1 n=2, grade 2 n=10, grade 3 or more n=5), fever (69%), and GI symptoms (47%). Univariate statistical analysis showed a correlation of HSR with lower baseline body weight (61 vs 69 kg) compared to controls, and borderline significance with white race (88% for cases vs 56% for controls). HSR cases had a similar frequency of IFN-y CD4 & IFN-y CD8 t-cells but had a significantly higher frequency of IL4 CD4 & IL4 CD8 t-cells compared to group 2 patients prior to starting abacavir. The study authors concluded an increased t-cell IL4 production seen is characteristic of other allergic states.