Co-immunization with altered peptide ligands neither induces regulatory T cells nor modulates CD25 expression. Mice were immunized with 10 μg glucose-6-phosphate isomerase hGPI325--339 and 50 μg each altered peptide ligand (APL), and draining lymph node cells on day 6 were stained with Foxp3 and CD25. Flow cytometry analysis was gated in CD4+ cells. None, immunization with no APL (hGPI325--339 alone). Representative flow cytometry data of two independent experiments.