Euglena gracilis paramylon activates human lymphocytes by upregulating pro‐inflammatory factors

The aim of this study was to verify the activation details and products of human lymphomonocytes, stimulated by different β-glucans, that is Euglena paramylon, MacroGard®, and lipopolysaccharide. We investigated the gene expression of inflammation-related cytokines and mediators, transactivation of relevant transcription factors, and phagocytosis role in cell-glucan interactions, by means of RT-PCR, immunocytochemistry, and colorimetric assay. Our results show that sonicated and alkalized paramylon upregulates pro-inflammatory factors (NO, TNF-α, IL-6, and COX-2) in lymphomonocytes. A clear demonstration of this upregulation is the increased transactivation of NF-kB visualized by immunofluorescence microscopy. Phagocytosis assay showed that internalization is not a mandatory step for signaling cascade to be triggered, since immune activity is not present in the lymphomonocytes that have internalized paramylon granules and particulate MacroGard®. Moreover, the response of Euglena β-glucan-activated lymphomonocytes is much greater than that induced by commercially used β-glucans such as MacroGard®. Our in vitro results indicate that linear fibrous Euglena β-glucan, obtained by sonication and alkaline treatment can act as safe and effective coadjutant of the innate immune system response.