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Immune responses to abacavir in antigen-presenting cells from hypersensitive patients

Martin, A., Almeida, C.M., Cameron, P.U., Purcell, Anthony W, Nolan, D., James, I., McCluskey, J., Phillips, E.J., Landay, Alan and Mallal, S. (2007) Immune responses to abacavir in antigen-presenting cells from hypersensitive patients. AIDS, 21 (10). pp. 1233-1244.

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OBJECTIVES: A potentially life-threatening hypersensitive reaction accompanies the use of HIV nucleoside analogue abacavir (ABC) in 4-8% of Caucasian individuals. HLA-B*5701 and Hsp70 493T alleles have been shown to predict susceptibility to this hypersensitivity. DESIGN AND METHODS: This study was undertaken to provide a mechanistic understanding of the highly significant genetic association of HLA Class I and Hsp70 alleles with ABC hypersensitivity. RESULTS: In this study an ABC-induced localization of intracellular HSP70 to endosomal vesicles of antigen-presenting cells was demonstrated. This ABC-stimulated redistribution of endogenous HSP70 was substantially higher in the genetically homogenous HLA-B*5701, Hsp70 493T ABC-hypersensitive individuals and ABC-naive individuals in comparison with the heterogenous tolerant patients (P = 0.023). Increased expression of HSP70 was also detected in the hypersensitive group as measured by flow cytometry (P = 0.032). Blocking of HSP70 and HSP70 cell surface receptors CD14 and TLR2 abrogated ABC-stimulated HSP70 redistribution in sensitized individuals to basal levels (P < 0.004). In addition, the use of TcRαβ and HLA-B57/58 antibodies also ablated the expression of HSP70. Cells expressing the activation markers CD40 were increased after ABC stimulation in the hypersensitive patients (P = 0.006). ABC-stimulated interferon-gamma levels were higher in hypersensitive patients in comparison with ABC-tolerant individuals with a mean of 123.54 versus 0 pg/ml (P = 0.001). CONCLUSION: The present data indicates that ABC stimulates an innate immune response and activates antigen-presenting cells via the endogenous HSP70-mediated Toll-like receptor pathway in genetically susceptible individuals potentially initiating the immuno-pathological hypersensitive response.

Item Type: Journal Article
Murdoch Affiliation(s): Centre for Clinical Immunology and Biomedical Statistics
Publisher: Lippincott Williams & Wilkins Ltd.
Copyright: © 2007 Lippincott Williams & Wilkins, Inc.
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