Deficiency in the Matk/CHK gene impairs the production of IFN-γ upon in vivo antigen challenge. (A) One week after immunization with TNP-Ova, lymph node cells were prepared from Matk/CHK^+/+ and Matk/CHK^–/– mice, and then challenged with varying concentrations of ovalbumin as indicated. Concentrations of the indicated cytokines (i-iv) were determined by ELISA assay in duplicate, as described in “Study design.” The means were derived from 3 animals in each group. The data (OD₄₅₀ value at 100 μg/mL and 1000 μg/mL ovalbumin) are summarized in Table 1. Results are from at least 3 independent experiments. (B) IL-12 expression levels in the lymph nodes (i) and serum (ii) derived from Matk/CHK^–/– mice and control mice, as determined by ELISA assay. The means were derived from 3 animals in each group. Results are from 3 independent experiments. (C) One week after immunization with TNP-Ova, spleen cells were prepared from Matk/CHK^+/+ and Matk/CHK^–/– mice, and then challenged with varying concentrations of ovalbumin as indicated. Concentrations of the indicated cytokines, IFN-γ (i) and IL-12 (ii), were determined by ELISA assay in triplicate as described in “Study design.” The means were derived from 3 animals in each group.