Comparison of Cytokines Expression from Human Monocyte-Derived Macrophages Infected with Different Species of Mycobacteria.

Cytokines have an important role in mounting effective host immune response against mycobacteria. Latent tuberculosis infection (LTBI) is an indication of containment of mycobacteria by the host immune response, whereas active TB is an indication of a failure of the immune response to contain . The dynamics of this host-immune response during infection experiment is believed to be indicative of behavior in the LTBI and active-TB cases. This relationship is, however, not fully elucidated. We investigated the cytokines expression at mRNA and protein level across 2 different protocols, that is, an protocol comparing human monocyte-derived macrophages (hMDMs;  = 12) infected with different species of mycobacteria, and a clinical protocol comparing TB-Antigen-Nil specimens from LTBI ( = 12) and active-TB ( = 12) cases. We found that infection of hMDMs with Bacillus Calmette-Guérin (BCG) and R179 showed increased colony-forming units at all time points postinfection. BCG-infected hMDMs demonstrated higher levels of 5 cytokines [interferon (IFN)-γ, interleukin (IL)-6, IL-1β, IL-12p40, and IL-12p70] at different intervals compared to R179. Compared to LTBI, active-TB cases had higher mRNA expression of IFN-α, IL-6, and IL-8, and lower expression of IFN-γ, IL-1α, IL-1β, IL-4, and tumor necrosis factor-α. Overall, we observed differential host responses at mRNA and protein levels during experimentally controlled infection, but no prominent differences were observed in the clinical protocol. Therefore, the result of the experiment model of cytokine response against mycobacteria should be interpreted cautiously when relating to LTBI and active-TB.