Serum IFN-γ and ALT in untreated and ConA-treated C57Bl/6 mice. C57BL/6 mice were injected with PBS or 12 mg ConA/kg. Serum was collected 3, 6, and 12 hr post- injection and processed for IFN-γ. IFN-γ values shown are mean (± SD) of three determinations for each sample (n = 3 animals/sample). ALT activities at 0, 3, 6, and 12 hr are from a single experiment (see Results).