Fig. 4
Peripheral tolerance induction in immunocompetent adults with gene-transferred peripheral B cells expressing engineered peptide-Ig
(A) Humoral and cellular tolerance induction. Nonirradiated BALB/c were injected with >1 × 107 LPS blasts co-cultured with retrovirus-producing F6P (+) or mock-transducing ψ-2 (−). One week later, mice were primed and boosted for humoral responses as before, and subsequently sacrificed 3 months later for analysis of splenic memory T cell responses (24). Cytokine release in individual splenic cultures was determined at 24 hr (IL-2) or 48 hr (IL-4); medium-alone background values were <1–2 U/ml and were subtracted for clarity (ΔU/ml). (B) Persistence of gene-transferred B cells. Hybridomas were also generated from spleens of tolerized mice by PEG fusion of A20 cells with LPS-activated splenocytes (48 hr, 50 µg/ml LPS). Hybridomas were selected in 1 mg/ml G418 and tested for their ability to activate the 9C127 T cell hybrid as above. Eight representative A20 hybridomas from each recipient (1–3) are shown.