Enhancement of antigen internalization by antigen-specific IgE. (A) BMMCs were pretreated with or without (green line) anti-DNP IgE (IgE; red line), washed, and crosslinked with DNP-OVA (IgE/Ag; black line) for 1 hour. Surface IgE was detected by flow cytometry. (B) BMMCs were pretreated with anti-DNP IgE (irrelevant IgE) or anti-OVA IgE, washed, and incubated with the indicated concentrations of Alexa Fluor 488-conjugated OVA for 1 hour or (C) 24 hours. (D) Anti-DNP IgE (green line) or anti-OVA IgE (red line) pretreated BMMCs were incubated with or without (black line) Alexa Fluor 488-conjugated OVA (5 μg/mL) or with unlabeled OVA (5 μg/mL; blue line) for 1 hour. (E) Anti-OVA (right) or anti-DNP (middle) pretreated BMMCs were incubated for 24 hours with 0.5 μg/mL Alexa Fluor 488-conjugated OVA (green fluorescence). BMMCs that received no OVA were used as a control (left). BMMCs were fixed and stained for choleratoxin to mark the cell surface (red fluorescence) and analyzed by confocal microscopy.