BDC cells were cultured for 3 days in the absence (culture (cx) only) or presence of stimulatory peptide without (Peptide Only) or with CTLA4Ig and anti-CD154 (combined costimulation blockade (cCoB)). Photomicrographs of cultured cells were taken (left panel). In addition cells were stained with CD3, CD4 and vβ4- florochrome-conjugated antibodies. CD3+, CD4+ and vβ4+ cells were identified via flow cytometry (where vβ4+ cells were regularly >90% of the CD3+, CD4+ population) and the side-scatted (SSC) versus vβ4 cells are shown (right panels). Peptide stimulate cells even in the presence of costimulation blockade go though some of the processes of activation, including blastogenesis and clumping. Shown are representative of more than 6 experiments.
