Modulating effect of a new ester, 28--phosphatidylbetulin (DAPB), obtained from hen egg yolk lecithin and betulin on lymphocyte subsets and humoral immune response in mice.

Leaf extracts of plants of the genus have traditionally been used as diuretic, anti-rheumatic and diaphoretic preparations. One of the main active ingredients of bark is betulin, lupane-type triterpene alcohol, with multiple biological activities. The aim of this study was to investigate and immunomodulatory effects of a newly synthesized ester of betulin: 28--phosphatidylbetulin [28--(1,2-diacyl--glycero-3-phospho)-betulin, DAPB] in comparison with betulin in mice. Cytotoxic activity of DAPB or betulin was tested against non-cancer (D10.G4.1 and J774E.1) and cancer (GL-1; CL-1 and Jurkat) cell lines. The part assessed total lymphocyte count, weight ratio and subsets of lymphocytes in the lymphatic organs, and humoral immune response to sheep erythrocytes (SRBC). assay showed that DAPB, contrary to betulin, had no antiproliferative activity. Exposure to four doses of DAPB increased the absolute count of immature CD4CD8 thymic cells as well as the percentage and absolute count of mature CD4 and CD8 thymocytes. DAPB enhanced the percentage or absolute count of CD3 cells in spleen and lymph nodes with corresponding decrease in the percentage and/or absolute count of CD19 cells. Both DAPB and betulin enhanced the percentage and absolute count of CD8 lymphocytes in lymph nodes. In SRBC-immunized mice, betulin contrary to DAPB enhanced the number of splenocytes producing anti-SRBC antibodies (PFC). Both DAPB and betulin increased the level of total (IgM + IgG) and IgG titers. Despite the lack of cytotoxic activity, DAPB shows valuable immunomodulatory properties.