In vivo application of E18 into healthy BALB/c mice. (A) Relative frequencies of Foxp3⁺ cells among CD4 single-positive thymocytes and CD4⁺ lymph node cells (B) were determined 7 days after intraperitoneal application of 250 μg of E18 or control mAb into BALB/c mice. Means plus or minus SD of 3 mice per group are depicted. (C) BALB/c mice received one injection per week of either PBS or 100 μg of E18 for a total of 25 weeks. Two and (D) 13 weeks after the last injection, lymph node cells were analyzed for the frequencies of Foxp3⁺ cells among CD4⁺ cells and the absolute numbers of CD4⁺ T cells. Means plus or minus SD of 3 to 4 mice per group and time point are depicted.