Israel Medical Association Journal

Abstract

Background: The mass influx of immigrants from tuberculosis-endemic countries into Israel was followed by a considerable increase in the incidence of tuberculosis (TB). All contacts of active TB patients are obliged to be screened by tuberculin skin tests (TST) and, if found positive, prophylactic treatment is considered.

Objectives: To assess the utility of interferon-gamma (IFNγ)-release assay with a prolonged follow-up in preventing unnecessary anti-TB therapy in individuals with suspected false positive results.

Methods: Between 2008 and 2012 the QuantiFERON TB gold-in-tube test (QFT-G) was performed in 278 sequential individuals who were mostly TST-positive and/or were in contact with an active TB patient. In all, whole blood was examined by the IFNγ-release assay. We correlated the TST diameter with the QFT-G assay and followed those patients with a negative assay.

Results: The QFT-G test was positive in only 72 (42%) of all 171 TST-positive individuals. There was no correlation between the diameter of TST and QFT-G positivity. Follow-up over 5 years was available in 128 (62%) of all QFT-G-negative individuals. All remained well and none developed active TB.

Conclusions: A negative QFT-G test may obviate the need for anti-TB therapy in more than half of those with a positive TST.

Background: Multiple drug allergy syndrome is a rarely reported clinical condition characterized by an adverse reaction to more than one different class of pharmacologically and structurally unrelated drugs. The pathogenesis may involve immediate-type or delayed-type hypersensitivity.

Objectives: To further characterize patients with MDA[1] in terms of the type of CADR, drug intake and clinical drug suspicion.

Methods: The study group comprised 12 patients (6 males, 6 females) with CADRs[2] showing in vitro drug-induced IFNγ[3] release for multiple drugs, suggesting the presence of MDA. The diagnostic role of in vitro IFNγ release in identifying the culprit drugs was evaluated in terms of clinical data and the results of in vivo tests (withdrawal and/or challenge tests) with the offending drugs.

Results: Clinical relevance was attributed to in vitro drug-induced IFNγ release towards multiple drugs in this series of 12 patients with a variety of CADRs, implying MDA. The results of in vivo tests for the offending drugs confirmed the diagnosis. The main causative agents responsible were antibiotics and non-steroidal anti-inflammatory drugs.

Conclusions: The study further supports the role of a T cell-mediated mechanism in the pathogenesis of MDA. The in vitro drug-induced IFNγ release test may serve as a laboratory tool to identify the culprit drugs associated with this allergy.  

Background Drug-specific CD8+ TH1 lymphocytes have been found in the peripheral blood and involved skin of patients with drug-induced bullous exanthems.

Objectives To determine whether the interferon-gamma release test can identify culprit drugs in pemphigus patients.

Methods Clinical and laboratory workup for pemphigus was performed in 14 pemphigus vulgaris patients who had been exposed to drugs, and the IFNl[1] release test was conducted on their lymphocytes from heparinized venous blood cultured with medium, phytohemagglutinin and one of 32 drugs, or medium and phytohemagglutinin alone.

Results Ten of the patients and 13 of the 32 drugs exhibited a positive response to the test. Eight of the 10 patients with positive IFNl test results had a less severe course of the disease, with fast reduction in steroid dosage.

Conclusions The findings demonstrate both the ability of the IFNl release test to identify drugs that can induce pemphigus, and its usefulness in the diagnostic workup of pemphigus patients.