Immunopotentiation of intraepithelial lymphocytes in the intestine by oral administrations of β-glucan

Mice were orally administered with β-glucan, isolated from baker’s yeast, daily for one week (25 mg/day/mouse) and several immunoparameters in the digestive tract were examined. The most prominent change was an increase in the number of intraepithelial lymphocytes (IEL) in the intestine, although the number of lymphocytes in the liver remained unchanged. The absolute number of both αβT cells and γδT cells expressing CD8 antigens increased among IEL in the intestine. Primarily, liver lymphocytes showed a spontaneous production of Type 0 cytokine (simultaneous production of IFNγ and IL-4) while IEL did not produce any cytokines without stimulation. However, mice administered with β-glucan produced Type 1 cytokine, namely, production of IFNγ alone. These results suggest that β-glucan may be an important potentiator for mucosal immunity in the digestive tract.