TCRβ/δ^−/− B6 mice received either purified CD4⁺ GFP⁺ RTEs or GFP⁻ MN T cells and were immunized the next day with NP-KLH in complete Freund adjuvant. Anti-NP IgG1 and IgG2a antibodies were detected in serum samples on days 14 and 21. The ratio of IgG1 to IgG2a was determined by dividing the IgG1 absorbance value by the IgG2a absorbance value at a serum sample of 1:8000 (a value on the linear portion of the titration curves for both IgG1 and IgG2a; see supplemental Figure 5). Data are mean ± SD for 4 individually analyzed mice per group. These data are representative of 3 independent experiments with similar results, for a total of 9 individually analyzed mice per group.