Royal jelly (RJ) is secreted by the hypopharyngeal glands of worker honeybee (Apis mellifera), and is widely used in the community as a health tonic. The present work was designed to examine the protective role of RJ against tumor in mice induced by Ehrlich ascites tumor (EAT) cell line and its possible anti-tumor mechanism of action. Peroral treatment of RJ (0.5, 5 or 50 mg/ 100 g BW) every other day for 4 weeks before the intraperitoneal inoculation of 1x106 EAT cells increased the total number of thymocytes and bone marrow lymphocytes as well as the absolute number of peritoneal macrophages. RJ pre-treatment to EAT-bearing mice also increased the phagocytic function of macrophages, as determined with carbon clearance assay; the activity of T cells, as determined by rosette- orming assay; and the activity of B cells as determined by plaqueforming assay. Furthermore, RJ pretreatment effectively decreased the proliferation of EAT cells in the peritoneal fluid, and decreased the viability of EAT cells in vitro. The size of solid Ehrlich tumor in the thigh muscle of mice was significantly decreased, as measured morphologically and examined histologically. In conclusion, these results point to RJ as a promising modifier of biological response leading to immunoprotection and anti-tumor activity in EAT model. RJ may enhance the host resistance against tumor through stimulating macrophage function, antibody production and immunocompetent cell proliferation.
Key words: Royal jelly, Ehrlich ascites tumor, Lymphocytes, Macrophages, T-cells, B-cells.
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