Figure 3.
CD4+ dendritic cells (DC) can phagocytose Escherichia coli and latex beads and present exogenous ovalbumin (OVA) on major histocompatibility complex (MHC) class I. (a) Flow cytometric analysis of 3-hr cultures of DC-enriched splenocytes and PKH26-labelled E. coli (left) or yellow green (YG) latex beads (right). Dot-plots represent gated CD11cbright cells. Numbers show the percentage of cells within each quadrant gate. (b) Quantification of E. coli uptake by double negative (DN), CD8α+ and CD4+ DC subsets. (c) Sorted CD4+ DC (open bars) and CD8α+ DC (filled bars) were cultured with OT-I T cells in the presence of two doses of OVA-E. coli or OVA/LLO-E.coli, as indicated. c.p.m., counts /min. (d) Sorted CD4+ (circles) and CD8α+ (triangles) DC subsets (3 × 104/well) were cultured with OT-I T cells and different doses of OVA-peptide in the absence (open symbols) or presence (filled symbols) of paraformaldehyde (PFA)-treated E. coli (106/well). Results in (c) and (d) represent the mean [3H]thymidine uptake of triplicate wells. All error bars are shown and represent 1 SD from the mean. Results are representative of (a) and (b) three experiments, (c) two experiments, or (d) one experiment, with a full peptide dose range and an additional experiment using selected peptide doses.