In vitro test to confirm diagnosis of allopurinol-induced severe cutaneous adverse reactions.
BACKGROUND
Allopurinol is a frequent cause of severe cutaneous adverse reactions (SCARs), such as drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). The reactions can potentially be fatal. As drug rechallenge in patients with a history of drug-induced SCARs is contraindicated, in vitro testing may have a diagnostic role as a confirmation test.


OBJECTIVE
To study the diagnostic value of interferon (IFN)-γ enzyme-linked immunospot (ELISpot) assay as a confirmatory test in patients with a history of allopurinol-induced SCARs.


METHODS
Peripheral blood mononuclear cells (PBMCs) from 24 patients with a history of allopurinol-induced SCAR (13 DRESS, 11 SJS/TEN) and 21 control subjects were incubated with allopurinol or oxypurinol in the presence or absence of antiprogrammed death ligand 1 antibody (anti-PD-L1). The numbers of IFN-γ-releasing cells after stimulation in each group were subsequently measured with ELISpot.


RESULTS
The numbers of IFN-γ-releasing cells in allopurinol-allergic subjects were significantly higher than in control subjects when stimulating PBMCs with oxypurinol 100 μg mL-1, especially when adding anti-PD-L1 supplementation. According to the receiver operating characteristic curve results, the optimal discriminatory power of IFN-γ ELISpot in confirming diagnosis of allopurinol-induced SCARs can be obtained using 16 spot-forming cells per 106PBMCs as a cut-off value upon oxypurinol/anti-PD-L1 stimulation (79·2% sensitivity and 95·2% specificity).


CONCLUSIONS
The measurement of oxypurinol/anti-PD-L1-inducing IFN-γ-releasing cells yields a high diagnostic value in distinguishing between allopurinol-allergic and control subjects. This technique is beneficial in confirming diagnosis of allopurinol-induced SCARs in patients whose reaction develops while taking multiple drugs.
Division of Allergy and Clinical Immunology, Department of Medicine, Faculty of Medicine, Allergy and Clinical Immunology Research Group, Chulalongkorn University, Bangkok, Thailand. jettanong.k@chula.ac.th.|King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand. jettanong.k@chula.ac.th.
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http://orcid.org/0000-0001-6063-2403
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Klaewsongkram
Division of Allergy and Clinical Immunology, Department of Medicine, Faculty of Medicine, Allergy and Clinical Immunology Research Group, Chulalongkorn University, Bangkok, Thailand.
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Thantiworasit
Division of Allergy and Clinical Immunology, Department of Medicine, Faculty of Medicine, Allergy and Clinical Immunology Research Group, Chulalongkorn University, Bangkok, Thailand.
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Suthumchai
King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand.|Division of Dermatology, Department of Medicine, Faculty of Medicine, Allergy and Clinical Immunology Research Group, Chulalongkorn University, Bangkok, Thailand.
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Rerknimitr
Division of Pharmacogenomics and Personalized Medicine, Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
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Sukasem
Department of Dermatology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
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Tuchinda
Department of Dermatology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
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Chularojanamontri
Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
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Srinoulprasert
Division of Allergy, Immunology and Rheumatology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
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Rerkpattanapipat
Division of Dermatology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
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Chanprapaph
Division of Dermatology, Department of Medicine, Faculty of Medicine, Thammasat University, Pathumthani, Thailand.
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Disphanurat
Division of Dermatology, Department of Medicine, Faculty of Medicine, Thammasat University, Pathumthani, Thailand.
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Chakkavittumrong
Dermatological Division, Department of Internal Medicine, Chiang Mai University, Chiang Mai, Thailand.
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N
Tovanabutra
Division of Dermatology, Department of Medicine, Phramongkutklao Hospital, Phramongkutklao College of Medicine, Bangkok, Thailand.
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C
Srisuttiyakorn
D000493:Allopurinol / Q000009:adverse effects*; D000906:Antibodies / Q000378:metabolism; D019540:Area Under Curve; D060890:B7-H1 Antigen / Q000276:immunology; D016022:Case-Control Studies; D004791:Enzyme Inhibitors / Q000494:pharmacology; D058501:Enzyme-Linked Immunospot Assay / Q000379:methods / Q000592:standards; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010117:Oxypurinol / Q000494:pharmacology; D013262:Stevens-Johnson Syndrome / Q000175:diagnosis* / Q000209:etiology
D000906:Antibodies; D060890:B7-H1 Antigen; C423236:CD274 protein, human; D004791:Enzyme Inhibitors; D000493:Allopurinol; D007371:Interferon-gamma; D010117:Oxypurinol