Fig. 2
Induction of peptide-specific cellular immune tolerance in adult bone marrow chimeras infused with peptide-Ig-expressing progenitor cells
BALB/c mice were sublethally irradiated (600 rads) and injected IV with 1−2 × 106 gene-modified or mocktransduced BM. Recipients were immunized with peptide in CFA 2 months post-infusion and draining LN cells were restimulated in vitro with dilutions of synthetic peptide and 25–50 µg/ml purified protein derivative (PPD, Connaught) in cRPMI 1640 with 0.5% heat-inactivated autologous serum. Stimulation indices (SI) represent ratios of proliferation to medium alone backgrounds (5,609 ± 2,271 cpm). IL-2 and IFN-γ were quantitated by CTLL and ELISA assays, respectively (24). Additional experiments also revealed a diminution of peptide-specific IL-4 release in LN of tolerized recipients (data not shown). Error bars signify standard error of the mean for 3 individual mice per group. This experiment was done at least twice with 3–4 mice per group with similar results.