FIG. 5.

Activation of DC by extracts from virulent versus avirulent strains of M. arthritidis. XS52 cells were treated with 1 μg/ml of extracts from all three strains of M. arthritidis. After 24 h, cells were harvested and stained with fluorescein isothiocyanate-conjugated anti-class II MHC or anti-CD40 antibodies or with phycoerythrin-conjugated anti-B7-1 or -B7-2 antibodies (open histograms). Isotype-matched control antibodies (filled histograms) were included in all experiments (see Materials and Methods). Flow cytometry data from a representative experiment of three are shown. (See text for P values.)