The measurement of drug-induced interferon γ-releasing cells and lymphocyte proliferation in severe cutaneous adverse reactions.

BACKGROUND: The lymphocyte transformation test (LTT) is a standard laboratory method to identify culprit drugs in patients with a history of drug-induced non-immediate hypersensitivity and is mainly performed during the recovery phase. The measurement of drug-specific interferon γ (IFN-γ)-releasing cells has been introduced to confirm culprit drugs, even during the acute phase of drug allergy. OBJECTIVES: This study aimed to evaluate the capability of the enzyme-linked immunospot assay (ELISpot) to detect drug-specific IFN-γ-releasing cells during the acute phase and the capability of LTT to identify culprit drugs during the recovery phase in patients presenting with severe cutaneous adverse reactions (SCARs). METHODS: Peripheral blood mononuclear cells (PBMCs) from 23 SCAR patients were collected during the acute and recovery phases and assayed for drug-specific IFN-γ-releasing cells and lymphocyte proliferation, respectively. RESULTS: Drug-specific IFN-γ-releasing cells were detectable in 73.9% of SCAR subjects (55.6% and 85.7% in patients who were and were not taking systemic steroids, respectively), whereas LTT results were positive in 52.2% of SCAR subjects. The frequencies of drug-specific IFN-γ-releasing cells were significantly higher in patients with positive LTT than in those with negative LTT (260.1 ± 110.0 and 46.6 ± 20.7 cells/106 PBMCs, P = 0.01). A significant correlation between the results of the IFN-γ ELISpot assay and LTT was demonstrated (r = 0.65, P value <0.01). CONCLUSION: The IFN-γ ELISpot assay could be a useful tool to identify culprit drugs in SCAR patients when culprit drug identification is urgently needed during the acute phase of drug allergy.

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. OBJECTIVES: 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 106 PBMCs 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.

Chronic generalized fibrotic skin lesions from disseminated leishmaniasis caused by Leishmania martiniquensis in two patients from northern Thailand infected with HIV.

BACKGROUND: Leishmaniasis is a newly emerging infection in Thailand. Most of the previous human cases have presented with the clinical features of visceral leishmaniasis and were mainly found in southern Thailand. Here we report the first two patients from northern Thailand presenting with disseminated cutaneous leishmaniasis. OBJECTIVES: To determine the nature of the infection of leishmaniasis and to identify the species of parasite responsible. METHODS: Clinical investigations included the taking of biopsy samples and histology. Parasitological diagnosis was performed by establishment of Leishmania promastigote cultures, and identification was performed by DNA sequencing of four independent gene loci (ribosomal RNA internal transcribed spacer 1; large subunit of RNA polymerase II; heat shock protein 70; RPL23a intergenic sequence). RESULTS: Both patients were infected with HIV, and had multiple cutaneous lesions and accompanying visceral leishmaniasis. They had similar cutaneous manifestations characterized by chronic generalized fibrotic lesions, which were more prominent on traumatic areas. In both patients the parasite was identified as Leishmania martiniquensis. This is a recently described species that is distinct and only distantly related to the classical agents of cutaneous leishmaniasis in Asia (Leishmania major and Leishmania tropica) or of visceral leishmaniasis (Leishmania donovani and Leishmania infantum). Each patient responded well to therapy with intravenous amphotericin B followed by oral itraconazole. CONCLUSIONS: Leishmania martiniquensis is a cause of cutaneous leishmaniasis in Thailand.