Assessment of macrophage and granulocyte cell-enhanced phagocytosis of Mycobacterium tuberculosis

Abstract

This study demonstrates the ability of a selected novel IgG1 mouse monoclonal antibody, JG7 III D3 I F9 (JG7), to enhance the phagocytic elimination (opsonophagocytosis) of susceptible M. tuberculosis strains at both their mid-logarithmic and stationary growth phases, by human U-937 macrophage and HL-60 granulocyte cell lines which are involved in intracellular killing of bacteria, and to assess the cytokine response to this process. The assays showed JG7-enhanced phagocytosis to all M. tuberculosis strains used, though at different levels. There was a relative increase in OPKA with increase in mAb concentration, at each bacterial dilution assessed (1:100 and 1:1000), and this increase was demonstrated mostly with the cMtb strain by the U-937 macrophage cell line. For the multiplex suspension array assays, the JG7 concentration of 25 µg/mL was selected, since it was used in both binding and OP assays. Results showed that the mAb induced a possible pro-inflammatory effect, driven by IL-8, in neutrophils and a significant anti-inflammatory response in MNL cells, as demonstrated by the significant decrease in pro-inflammatory IL-12p70 and increase in anti-inflammatory IL-10.