Initial studies implied that glucan was especially active in the activation of the phagocytic apparatus. Later studies, focused on cell-mediated immunity, confirmed these findings and for many years glucan was used as a non-specific macrophage stimulator. This is extremely important in the organism because macrophages represent the first line of defence and the body is not able to defend itself successfully without their optimum activity. Glucans therefore not only trigger respiratory inflammations, but also stimulate the production of many immunoactive substances, for example IL-6, IFN and TNFα.

These non-specific effects were later attributed especially to insoluble or high-molecular products that bind to macrophages non-specifically or are merely phagocytized. Changes in the cytokine production are probably in some relation to the process of escalation of functional activities of the glucan-stimulated macrophages. The growth-transforming factor TGFβ stimulates macrophages to secrete lysosomal hydrolases. But cytokines also act the other way round, IL-1 jointly with TNF have a regulatory effect on the expression of glucan-induced modulation of the macrophage functions.

Soluble glucans with a low molecular weight do not affect the production of cytokines too much and act by means of other mechanisms. These glucans bind to a receptor called CR3 (CD11b/CD18). When glucan is bound, there is a conformance change of the receptor and its specific activation. These receptors are present on macrophages, neutrophil granulocytes and NK cells. CR3 receptors are considered as extremely important receptors mediating the bond and elimination of immunity complexes opsonized by the iC3b component of the complement. The mechanism of activation of this receptor is triggered by the glucan bond, which is followed by cytotoxic de-granulation after the iC3b fragment binds to another part of the CR3 molecule. Without glucan activation, these receptors bind opsonized particles but there is no specific cell destruction.

At present, three big clinical trials are being conducted by the top US-based Sloan-Kettering Institute, using the activity of Beta-Glucan to support the treatment of neuroblastomas using monoclonal antibodies and the preliminary results look very promising. Similar studies observing the effects of glucan on lung cancer are underway in Kentucky, while its effects on intestinal cancer are researched in clinical trials in the Philippines.