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A rapid and sensitive flow-based screening test for detection of HLA-B57 to avoid abacavir hypersensitivity
Conference presentation

A rapid and sensitive flow-based screening test for detection of HLA-B57 to avoid abacavir hypersensitivity

L. Kostenko, A. Lucas, L. Kjer-Nielsen, B. Foley, I. Nicholson, B. Tait, R. Holdsworth, J. Rossjohn, S. Mallal and J. McCluskey
4th International AIDS Conference on HIV Pathogenesis, Treatment and Prevention (Sydney, Australia, 22/07/2007–25/07/2007)
2007
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Abstract

Objectives: About 5-10% of HIV-1 patients treated with Abacavir develop a hypersensitivity reaction characterised by systemic symptoms which resolve when treatment is discontinued. The presence of HLA-B*5701 is a strong predictor of Abacavir hypersensitivity and pre-screening of patients for HLA-B*5701 reduces the incidence of Abacavir hypersensitivity. However, current DNA-based methods of HLA-B*57 typing (SBT) are slow and expensive. Screening by Flow cytometry offers logistical advantages when combined with the routine CD4 T cell enumeration and potentially provides a 1-2 day turnaround. Methods: A mAb that reacts with members of the HLA-B57 and B58 serological group (anti-HLA-B17) was generated and optimised for flow cytometry-based assay. Results: Screening of ~70 consecutive normal blood donors with known HLA genotype and staining of Labscreen beads coated with disparate HLA class I allotypes verified the mAb, 3E12, has 100% sensitivity for HLA-B57/B58. A pilot exchange program confirmed the utility of the mAb in a single-step flow cytometry-based assay, using whole blood and either fresh or frozen/thawed PBMCs. The mAb was used to screen frozen PBMCs from 601 HIV-infected patients participating in the PREDICT-1 clinical trial and compared to sequence-based HLA typing . The sensitivity of the mAb typing was again 100%. Conclusions: Our findings suggest that the 3E12 mAb provides a basis for a rapid Flow-based screening test to identify patients with HLA-B57/B58 prior to treatment with abacavir. Given the combined phenotype frequency of HLA-B57 and B58 in most populations is 5-8%, screening with mAb 3E12 would allow >90% of patients to start therapy without further HLA-testing. Patients who screened positive for the mAb would be referred for DNA-based HLA-genotyping. The screen also offers the possibility of rapid and simple point-of-care test adaptable for developing nations.

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