Activation of B lymphocytes by GLIS, a bioactive proteoglycan from Ganoderma lucidum

A bioactive fraction (GLIS) was isolated from the fruiting body of the fungus Ganoderma lucidum using successive chromatographic steps. GLIS is a proteoglycan and has a carbohydrate: protein ratio of 11.5 : 1. The carbohydrate portion is composed of seven different monosaccharides, predominantly D-glucose, D-galactose and D-mannose in the molar ratio of 3.0 : 1 : 1.GLIS stimulated the proliferation of mouse spleen lymphocytes, resulting in a three to four-fold increase in the percentage of B cells. GLIS also activated mouse spleen lymphocytes, and most of the activated cells were B cells. The B cells were enlarged, expressed CD71 and CD25 on the cell surface, and showed an increase in the secretion of immunoglobulin. Lymphocytes also showed a slightly increased production of IL-2, whereas the secretion of IL-4 was not influenced by GLIS. Furthermore, GLIS did not influence the intracellular Ca2+ concentration of lymphocytes, but it enhanced the expression of protein kinase C alpha and protein kinase C gamma in B cells. According to our results GLIS is a new B cell-stimulating factor.