FIGURE 4.

Combinatorial effect of C. jejuni lipooligosaccharide sialylation, amide linkages, and phosphorylation on TNF-α induction in THP-1 cells. Supernatants from THP-1 cells stimulated with 10 ng/ml isolated LOS (A), 100 ng/ml isolated LOS (B), or live bacteria at a multiplicity of infection (MOI) 10 for 20 h (C) were assessed for TNFα levels by ELISA. To show the combined influence of all three modifications (sialylation, amide linkage, and phosphorylation) on TNFα levels, the relative abundance of two amide and three amide linkages plus 3 or 4 phosphoryl residues were added to either 100 (for strains containing 2 SA residues) or 50 (for strains containing 1 SA residue). TNFα levels were plotted against this relative score out of 300 for these modifications. Data points represent mean values for an individual strain from a minimum of four independent experiments. Linear regression analyses were performed.