Figure 2.

Viable bystander DCs acquire antigenic material from MΦ induced to undergo apoptosis by infection with wild-type S. typhimurium. (a and c) OVA peptide presentation on MHC-I (K^b) and (d and f) MHC-II (I-A^b) by bystander DCs quantitated using the OVA(257–264)/K^b– or the OVA(265–277)/I-A^b–specific T cell hybridoma CD8OVA or OT4H.2D5, respectively. MΦ (H-2^d) were coincubated for 90 min with either stationary phase (stat) 14028r, logarithmically growing (log) 14028r, or logarithmically growing CS022r expressing Crl-OVA as indicated. After washing and addition of gentamycin, live (+ DC) or paraformaldehyde-fixed (+ fixed DC) (H-2^b) or no DCs (− DC) and T hybridoma cells were added as indicated. (b and e) The CD8OVA (b) or OT4H.2D5 (e) response to live or fixed DCs (H-2^b) loaded with 1 nM OVA(257–264) or 100 μM OVA(265–280) peptide, respectively. Counts per minute in wells where bystander DCs were omitted or where DCs or MΦ were incubated in medium only along with the appropriate T cell hybridoma were typically 250–2,500. The results are representative of three to five independent experiments.