Figure 3.

Prior occupancy of G_M1 does not influence presentation of intact antigen or preprocessed peptide. A20µWT cells were preincubated with 30 µg/ml of Escherichia coli enterotoxin B subunit (EtxB) for 21 hr at 37°. Cells were then washed to remove EtxB. The cells were then either incubated with increasing concentrations of ovalbumin (OVA) or phosphorylcholine (PC)-OVA (a), or fixed with 1% paraformaldehyde and incubated with OVA_323–339 for 1 hr at 37° (b). DO.11 cells were added and incubation was continued for an additional 18–20 hr. Supernatants were analysed with interleukin-2 (IL-2)-responsive HT-2 cells. Data represent mean proliferation of quadruplicate samples ± standard error of the mean (SEM). Numbers after antigen (a) indicate the dose (in µg/ml) used. The data represent two similar, independent experiments. c.p.m., counts per minute.