Figure 2

The number of CD4⁺CD25⁺-expressing regulatory T cells from BALB/c and C57BL/6 mice during immunization. (a) BALB/c and C57BL/6 mice, immunized with proteoglycan (PG) or ovalbumin (OVA), were killed at 14 days after each immunization, and levels of expression of the CD4⁺CD25⁺ T cells were determined by flow cytometry. *The CD4⁺CD25⁺ T cells from naïve BALB/c and C57BL/6 mice were also determined. (b) Cytotoxic T-lymphocyte antigen (CTLA)-4 expression on the CD4⁺CD25⁺ T cells from PG- or OVA-immunized animals (after the 3rd injection) was determined.