A comparative analysis of tuberculosis in vitro screening in pemphigus patients selected for treatment with rituximab

INTRODUCTION: Patients qualified for the Polish government programme of treating severe pemphigus diseases with rituximab (RTX) available in 2018-2019 had to meet numerous criteria, including no active infectious disease. AIM: The clinical usefulness of tuberculosis screening with the QuantiFERON-TB Gold Plus (QFT-Plus) in native pemphigus patients selected for RTX treatment was statistically evaluated. MATERIAL AND METHODS: Eighteen pemphigus patients were examined with QFT-Plus prior to the intended RTX therapy. Ninety hospital employees examined with QFT-Plus due to contact with a cleaning worker who was diagnosed with active pulmonary tuberculosis were the control group. RESULTS: Six of 18 pemphigus patients had a positive QFT-Plus test result, one indefinite result and one initially indefinite and then negative. In the control group, 26 of 90 employees had a positive test result and none had an indefinite result. Statistical analysis by Fisher’s exact test showed no statistically significant difference in QFT-Plus positive results between the groups (p = 0.5577). Only in 1 patient with recurrent mucocutaneous pemphigus vulgaris previously treated with traditional immunosuppression, lung changes were detected by computed tomography. No employee had any changes in the chest radiograph. CONCLUSIONS: Prior immunosuppression and autoimmunity might be the cause of indefinite test results, but they do not seem to increase positive results. In the native population, the QFT-Plus screening reveals a significant population exposure to M. tuberculosis infection independent of pemphigus autoimmunity, and such screening can be a starting point for identifying patients requiring anti-tuberculosis drug prophylaxis before combined RTX-glucocorticosteroid treatment.