Flt3L enhances activation-induced cell death of CD4⁺ T cells in response to antigen, an effect that is not further enhanced by rapamycin. (A-B) Depletion of OVA-specific CD4⁺ T cells in spleens of DO11.10-tg Rag-2^−/− BALB/c mice treated with OVA_323-339, Flt3L, Flt3L/OVA_323-339, or a combination of Flt3L/OVA_323-339/rapamycin. Untreated, naïve animals served as controls (n = 5 per experimental group). (C) Percentage of CD4⁺ T cells showing early apoptosis (Annexin V⁺7-AAD⁻) after treatment with OVA_323-339 or Flt3L/OVA_323-339, compared with untreated control animals. Expression of activation markers CD62L (D), CD44 (E) and CD69 (F) in mice treated with OVA_323-339 or Flt3L/OVA_323-339, or in naïve, untreated animals. Data are average ± SD. Statistical differences were determined by 2-way ANOVA with Dunnett’s multiple comparison posttest analysis, using data from naïve mice as a control group, against which the other treatment groups were tested.