Plasma Macrophage Migration Inhibitory Factor Concentration at Each Spectrum of Tuberculosis

Macrophage migration inhibitory factor (MIF) is an inflammatory mediator in several diseases, including tuberculosis (TB). However, the role of MIF in each stage of TB remains to be further elucidated. Thus, this study aimed to analyze the differences in plasma MIF protein levels in patients with active pulmonary TB, positive and negative interferon-gamma release assay (IGRA) household contacts (HHCs), and healthy controls (HCs). Plasma MIF concentration was significantly higher in patients with active-new pulmonary tuberculosis (ATB) and HHCs compared with HCs (mean ± standard deviation: 17.32 ± 16.85, 16.29 ± 14.21, and 7.29 ± 5.39 ng/mL, respectively; P = 0.002). The plasma MIF concentration was not statistically different when compared between patients with ATB, IGRA-positive HHCs (17.44 ± 16.6 ng/mL), and IGRA-negative HHCs (14.34 ± 8.7 ng/mL) (P = 0.897). In conclusion, ATB patients, IGRA-positive HHCs, and IGRA-negative HHCs have a higher MIF concentration than HCs. This shows the involvement of MIF in each stage of TB, starting from TB exposure and infection, but not symptomatic, to the active stage.