Fig. 5.

Exponential immunization delays DC recruitment. C57BL/6 mice were immunized with gp33 peptide and CpG according to the immunization protocol s1 (bolus injection) and s4 (exponentially increasing doses) as described in Fig. 1. The vaccines were administered s.c. in the inguinal region. After 1, 4, 6, and 8 days, the iLN were removed, and single cell suspensions thereof were analyzed by flow cytometry for the expression of the DC marker CD11c, as well as CD86 and the MHC class II marker I-Ab (A). The results in the Top are illustrated as the relative frequency of cells expressing both CD11c and I-Ab. The Middle illustrates the relative MFI of CD86 expression and the Bottom the relative MFI of I-Ab expression on DCs. In all cases, the results are normalized to that of naive controls (day 0) for which reason the starting point is always 100. Mice were also immunized with gp33 peptide and CpG according to modified protocols as illustrated (B). One group received a CpG bolus on day 3 and a gp33 peptide bolus on day 4. One group received exponentially increasing CpG doses on days 0–3 followed by a gp33 peptide bolus on day 4. The last group received exponentially increasing doses of gp33 peptide and CpG on days 1–4 as described above (s4). The frequency of IFN-γ-producing CD8 T cells was measured in peripheral blood on day 10. The results show means and SEM of one of two comparable experiments (n = 3).