FIG. 1.
Borrelia-induced tolerance in human PBMC. Human PBMC (106) from four healthy donors were incubated with culture medium (con), 10 μg of Borrelia lysate/ml, 7 × 105 heat-inactivated Borrelia cells (heat-inact. Bb), or 2 × 105 live Borrelia cells for 24 h and then washed and incubated for another 24 h in the presence of 10 μg of Borrelia lysate/ml (a), 7 × 105 heat-inactivated Borrelia cells (b), or 2 × 105 live Borrelia cells (c). The concentrations of TNF-α were measured by ELISA. Data are expressed as the means ± SEM divided by the optical density (OD) assessed by the MTT assay. The statistical significance is for comparison with the nontolerized (con) cells. * represents a P value of <0.05 and *** represents a P value of <0.001 based on ANOVA followed by Dunnett's multiple comparison test.