Characterization of immune responses of human PBMCs infected with Mycobacterium tuberculosis H37Ra: Impact of donor declared BCG vaccination history on immune responses and M. tuberculosis growth

Abstract

This study characterized the immune responses in early Mycobacterium tuberculosis (Mtb) H37Ra infection of human peripheral blood mononuclear cell (PBMC)-collagen matrix culture and the impact of Bacille Calmette-Guérin (BCG) vaccination history of donor PBMCs on the immune responses to Mtb infection. Aggregates of PBMCs were initially observed on day 3 and the size of aggregates continued to increase on day 8 post-infection, where macrophages and T cell subsets were identified to be present. Similarly, mycobacterial load progressively increased in infected PBMCs during the 8 days of culture but were significantly lower in infected PBMCs from BCG vaccinated (BCG+) donors compared to unvaccinated (BCG-) donors. The levels of INF-γ, TNF-α, IL-4, IL-6, IL-10 and IL-17 in the supernatants of Mtb-infected PBMCs peaked at day 3 and decreased on days 5 and 8. The levels of these cytokines except IL-10 were significantly lower in Mtb-infected PBMCs from BCG+ donors compared to infected PBMCs from BCG- donors. The percentages of activated naïve Th cells, activated effector memory Th cells and activated central memory Tc cells were significantly higher in Mtb-infected PBMCs compared to uninfected PBMCs at day 8 post-infection. Further, the proportion of activated central memory Tc cells was significantly higher in infected PBMCs from BCG+ donors compared to the BCG- donors. This study highlights the possibility that BCG vaccination may confound results that utilize human PBMCs to study Mtb infection.

Modelling early events in Mycobacterium bovis infection using a co-culture model of the bovine alveolus

“…The preparation of CM was performed using PBMC cultures on 2D plastic to maximise supernatant recovery post infection. At 7 days, many aggregations were observed, which the authors propose to be multi-nucleated giant cells (MGCs), in line with previous observations 57 , 66 , 67 . MGCs are known to arise from the fusion of multiple macrophages in response to mycobacterial infection in cattle 68 – 70 .…”

“…Previous investigations into the relationship between cytokine and chemokine expression in the context of BCG vaccination have highlighted the role of IL17 and IL22 as biomarkers of a vaccine protected phenotype 55 , 56 . Additionally, a recent study into the impact of donor vaccination history upon early events in M. tuberculosis infection demonstrated a lower level of expression for multiple cytokines, including IL17, and decreased mycobacterial load in PBMCs from BCG vaccinated donors 57 . During the current study, in a researcher blinded experiment, this relationship was examined using PBMCs from cattle exhibiting a strong vaccine protected phenotype (VPP) (PBMC sample 1412) and compared with PBMCs from naïve cattle (PBMC sample 1406).…”

Evaluation of IFN-? level in peripheral blood mononuclear cell of childhood tuberculosis treated by lactic acid bacteria multi cultures

“…The Mtb and Mycobacterial product are strong inducers for IL-12. Secretion of IL-12 will collaborate indirectly with IL-1 and TNF to stimulate T cells and NK to produce IFN-γ [5,15].…”

“…This is one of the factors that complicated treatment [4]. There is an important role for macrophages and T cells in destroying Mtb by which the macrophages activated produce several cytokines including interleukin (IL) 12 which can stimulate the IFN-γ production by Th1 cells and Natural Killer (NK) cells [5,6]. The IFN-γ is tasked to strengthen the potential of phagocytes from macrophages infected with the Mtb by stimulating the formation of phagolysosomes and free radicals to destroy DNA and cell walls of Mtb so that growth is inhibited and subsequently eliminated [4,7].…”

“…Bhavanam et al reported characteristic of immune responses of human peripheral blood mononuclear cell (PBMC) infected by Mtb H37Ra [5]. Level of the IFN-γ and other immune parameters were observed at three until eight days after treatment.…”