FIG. 3.

Cytokine expression in C57BL/10SnJ glial cells exposed to scrapie agent-infected brain homogenate. (A) Exposure to scrapie agent-infected or healthy uninfected brain homogenates. Purified microglia (MG) or astroglia (AG) were stimulated by overlay with scrapie agent-infected or healthy brain homogenates. Supernatants were analyzed by multiplex assay 24 h after stimulation. The data show the scrapie agent-induced cytokine level as explained in Materials and Methods. Statistical analysis was done using the Wilcoxon matched-pair test comparing the S and N values for cultures from 16 independent experiments for each cytokine (6 experiments for CXCL10). Subtracted values for scrapie agent-infected brain stimulation minus healthy brain stimulation (S − N) are shown (see the legend to Fig. 2 and Materials and Methods for details). The cytokine levels from microglia are shown as solid circles, and the cytokine levels from astroglia are shown as open circles. MG produced IL-12p40 and CXCL10, and AG produced these two cytokines plus CCL2, CCL3, CCL5, G-CSF, IL-1β, IL-6, IL-12p70, IL-13, and CXCL1 (not shown). Statistical significance by the Mann-Whitney matched-pair test is indicated as follows: *, P < 0.05; **, P < 0.005; ***, P < 0.001; ns, not significant. (B) Stimulation of glia by LPS. Supernatants of microglia and astroglia cultures stimulated for 24 h with LPS at a concentration of 1 μg/ml were analyzed for cytokines using Bio-Plex multiple-cytokine assay kits. The values represent the means plus standard errors of the means (error bars) for seven different experiments.