FIG 2.

Nasal S. aureus isolates have qualitatively different IL-10-inducing ligands embedded in their cell walls. (A and B) Human PBMCs were stimulated with protoplasm (PP) or cell wall (CW) fractions of the S8 S. aureus isolate for 18 h. (C and D) PBMC response to heat-killed bacteria (HK) (MOI = 5) or supernatants (Sup) (1% of overnight culture). (E and F) Human PBMCs were stimulated with increasing amounts of two representative S. aureus isolates inducing low-level (S5; circles and solid line) or high-level (S8; squares and dashed line) IL-10 responses for 18 h. Quantification of IL-10 (A, C, and E) and TNF-α (B, D, and F) in the supernatants was performed by ELISA. Data are plotted as means ± SEMs for 3 to 5 different donors in experiments performed in triplicate. Statistical analysis was performed using ANOVA with post hoc Bonferroni test (A, B, E, and F) or Student t test (C and D). *, P < 0.05; **, P < 0.01; ***, P < 0.001.