Abstract: Objective: To investigate the value of interferon-γ release assay (IGRA) in the diagnosis of Mycobacterium leprae infection. Methods: IGRA was detected in PBMCs of leprosy patients and healthy people. The frequency of IFN-γ releasing effector T cells was detected by I-SPOT-TB kit (enzyme-linked immunospot assay) in the multibacillary (MB) and paucibacillary (PB) leprosy patients. Comparative analysis of IGRA test positive rate between MB and PB patients, and the IGRA test combined with qPCR was discussed and analyzed in PB patients. Results: Based on the pathological diagnosis of patients, 29 leprosy patients and 20 healthy people were enrolled as controls. There was no significant difference of IFN-γ activation and IGRA positivity rate between MB and PB patients. 37.5% of PB patients were qPCR negative but IGRA positive. 12.5% of PB patients were IGRA negative but qPCR positive. The percentage of IGRA positive or qPCR positive PB patients was 75%. Conclusion: Positive result of IGRA suggests the possibility of Mycobacterium leprae infection. IGRA combined with qPCR may be an auxiliary detection method for early screening of leprosy.

Key words: Interferon-γ release assay (IGRA), Mycobacterium leprae infection