Interferon-γ (IFN-γ) secretion from splenocytes isolated from BALB/c after intranasal (IN) immunization (small volume). BALB/c mice (n = 5) were immunized by IN inhalation of 10 µg of HBsAg alone (none) or with 1, 10, or 50 µg cholera toxin (CT) and/or CpG-containing oligodeoxynucleotides (CpG) as adjuvants in a volume of 20 µl. Mice were boosted at 4 and 8 weeks. Culture supernatants taken at 96 hr from Ag-stimulated splenic T cells from mice in these groups were examined by ELISA for IFN-γ. Each circle represents the level of IFN-γ in culture supernatant from an individual mouse expressed in pg/ml. HBsAg, purified hepatitis B surface antigen.