The ß-glucans resemble the polysaccharide chains on the outer cell wall of bacteria. This simulates the penetration of pathogens and trains the defense system. ß-glucans are not synthesized by the human organism. Therefore, the immune system recognizes them as foreign to the body, so they stimulate both innate and acquired immune responses.
To put it more precisely: ß-glucans have similar molecular properties to pathogens. They are therefore recognized by certain cell surface receptors and trigger an immune response. These receptors are dectin-1, the complement receptor, the scavenger receptor, LacCer (lactosylceramide), and the TLR (toll-like receptor). These are the receptors through which ß-glucans mediate their effect.
Dektin-1 is a lectin and is found on macrophages, neutrophil granulocytes, dendritic cells, and T cells. ß-1-3- and ß-1-6-glucans bind to it. This binding leads to the activation of phagocytosis, which stimulates the production of ROS, TNF-alpha, IL-2, IL-10, and IL-12.
The complement receptor is found on neutrophil granulocytes, monocytes and NK cells. ß-glucans and numerous pathogens bind to it. This triggers a cytotoxic effect on tumor cells.
The scavenger receptor is found on endothelial cells and myeloid cells (monocytes, granulocytes). LDL, HDL, various exogenous cells and lentinan bind to it. This activates various kinases and eNOS.
LacCer on neutrophil granulocytes leads to ROS formation; LacCer on epithelial cells to the synthesis of TNF-alpha and NF-kappa B. ß-glucans and microbial cells bind to it.
The Toll-like receptor TLR is found on macrophages, lymphocytes, dendritic cells and epithelial cells. It reacts to fungi, bacteria, viruses and protozoa, producing NFkappa B and cytokines (TNF-alpha, IL-12).
The effect on the innate nonspecific immune response is to increase cytotoxicity and cytokine production by macrophages, natural killer cells, and neutrophil granulocytes. They also act against degenerate cells, viruses and bacteria through the production of free oxygen and nitrogen radicals (NO gas).
The effect on the acquired immune response is the activation of dendritic cells. These are derived from monocytes and present antigens to T cells. ß-glucans also stimulate the production of the cytokines and chemokines IL-8, IL-1b, IL-6, and the tumor necrosis factor TNF-α. Furthermore, the ability of macrophages to recognize and eliminate cells undergoing apoptosis.
ß-glucans show significant effects in animal and clinical studies. Among them, an antiviral effect in HIV (CD4 cells increase), hepatitis B (stimulation of phagocytosis) and swine flu virus (decrease of viral nucleic acids in infected animal cells, the increase of interferon gamma and NO gas), and generally an antibacterial and antifungal effect. Wound healing is also supported by increasing the activity of macrophages.
In addition, a direct cytotoxic effect on cancer cells by polysaccharides was discovered. Thus, both carcinogenesis and tumor progression can possibly be halted by ß-glucans. Active polysaccharides are also dietary fibers that can absorb potential carcinogens and promote their excretion through the intestine.