Signaling via the FasL ICD modulates the immune response following immunization with NP-CGG. Wild-type and FasL ΔIntra mice were immunized with 100 μg of the TD antigen NP-CGG (left panel) or with 50 μg of the TI antigen NP-Ficoll (right panel; both intraperitoneal injections) and killed 14 days (NP-CGG) or 7 days (NP-Ficoll) later. The amount of Syndecan⁺B220^low plasma B cells (A,D) and CD95⁺PNA⁺ GCs (B) was determined by FACS analysis of splenocytes. The data represent results from 2 immunization experiments, each time with 4 (NP-CGG) or 5 (NP-Ficoll) mice per group. The columns represent mean values of the individual animals, and the bars indicate the standard error. (C,E) Titers of antigen-specific, NP17-binding IgM, IgG1 (C), or IgG3 (E) antibodies in the serum of immunized animals were determined by ELISA. Each symbol represents 1 mouse, and the vertical bar indicates the mean value per group. Immunglobulin titers in the serum of wild-type mice are represented by filled hash keys and titers in FasL ΔIntra mice by open rectangles.