Fig. 3.

Quantitation of bead-associated fluorescence. (A) DC vs. B blast bead-induced clustering. The percentage of beads in contact with I-E-GFP-expressing APCs with enrichment of I-E upon incubation with I-A or I-E beads was quantified. DCs, filled bars; B blasts, open bars. (B) DC-specific vs. nonspecific clustering. Enrichment of I-E fluorescence at sites of bead contact vs. elsewhere on the same cell were quantified by fluorescence intensity (see Materials and Methods); fold enrichment of I-E clustering by I-E or I-A beads is shown. (C) Effect of methyl-β-cyclodextrin treatment. After adhering DCs to coverslips, they were treated with 30 mM methyl-β-cyclodextrin, beads were added and processed as above, and fold enrichment of I-E by I-E and I-A beads was measured. Fold enrichment without (filled bars) and with (open bars) cyclodextrin treatment was normalized to without treatment.