Particulate beta-glucan induces early and late phagosomal maturation in murine macrophages.

Beta-glucans are carbohydrates (glucose polymers) found in the cell walls of fungi, yeast, algae, lichens, and plants such as oats and barley. Beta-glucans bind to glucan receptor on phagocytic cells and modify these cells to become "immunologically active" by generating a variety of innate immune responses. Particulate beta-glucan has been specifically shown to engage dectin-1 receptor, which leads to the recruitment and activation of nicotinamide adenine dinucleotide phosphate oxidase-2 (NOX-2) and release of antimicrobial reactive oxygen species (ROS). Here, we report that yeast-derived beta-glucan particles (YDGP) of a specific size are easily phagocytosed by macrophages and induce the production of ROS. Furthermore, the present work also demonstrates that phagosomal maturation, appearance of acidic vesicular compartments (AVO), and light chain protein-3 (LC3) accumulation within murine macrophages, occur at early and delayed time points after the phagocytic uptake of YDGP. These data suggest that particulate glucans can be exploited to trigger autophagy within phagocytes and, thereby, have implications in antimicrobial therapy.