Factors influencing phytohemagglutinin response in gamma-interferon release assay / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the factors influencing phytohemagglutinin (PHA) response in the detection of Mycobacterium tuberculosis infection by gamma interferon release assay (IGRA). Methods:A retrospective case-control study was conducted on 360 hospitalized patients who received IGRA in West China Hospital of Sichuan University from January 2019 to December 2021. According to PHA response (IFN-γ level), they were divided into three groups: negative mitogen response group (IFN-γ<2 pg/ml), weak positive mitogen response group (IFN-γ: 2-100 pg/ml), and normal mitogen response group (IFN-γ>400 pg/ml).Results:Immune diseases were independently associated with negative (OR=0.34, 95%CI: 0.17-0.72, P=0.004) and weak positive mitogen responses (OR=0.29, 95%CI: 0.16-0.55, P<0.001). Infections caused by pathogens other than Mycobacterium tuberculosis was independently associated with negative mitogen response (OR=0.266, 95%CI: 0.09-0.83, P=0.023), while immunodeficiency was independently associated with weak positive mitogen response (OR=0.280, 95%CI: 0.12-0.63, P=0.002). Mitogen response was significantly correlated with the levels of albumin and hemoglobin in serum and the counts of neutrophils and lymphocytes ( P<0.001). Conclusions:Immune diseases and immunodeficiency can affect mitogen response. Therefore, clinicians should give attention to mitogen response in the interpretation of IGRA test results to prevent misdiagnosis and underdiagnosis. Besides, to a certain extent, mitogen response can reflect the infection status of hospitalized patients.