Analysis of cytokines induced by the oral administration of γ-PGA. BALB/c mice (6 weeks old, n = 10 per group) were given 2,000-kDa γ-PGA (50 mg/kg of body weight) in 100 µl saline once daily for five days. Blood samples were collected before (day 0) or 4 h after administering γ-PGA on day 1, 3, or 5 to measure titers of IFN-β (a), IFN-α (b), and other cytokines (c) by ELISA. In all panels, data are mean ± s.d. **P < 0.01; ***P < 0.001; n.s., not significant; by two-tailed unpaired Student’s t-test. LOD, limit of detection.