FIGURE 1.

Glycosaminoglycans inhibit Factor H-mediated pneumococcal adhesion to human lung epithelial cells. A, adherence of pneumococci via Factor H to lung epithelial A549 cells in the absence (control) or the presence of heparin (50 units/ml), dermatan sulfate (100 μg/ml), or after pretreatment with heparinase III (10 milliunits/ml) was estimated by quantifying the colony-forming units (cfu) per well obtained from plating onto blood agar plates. The infection assays were conducted with or without (none) pretreatment of pneumococci with Factor H. *, p < 0.02. B, immunofluorescence microscopy of Factor H-mediated pneumococcal adhesion after treatment of host cells with glycosaminoglycans or heparinase III. Adherent bacteria appear green/yellow (Alexa Fluor 488/568), and intracellular bacteria were stained red (Alexa Fluor 568). C and D, pneumococcal invasion into epithelial cells via Factor H is diminished in the presence of glycosaminoglycans. Pneumococcal invasion was determined after conducting infection assays in the absence (control) or presence of glycosaminoglycans by employing the antibiotic protection assay. *, p < 0.001 relative to infections carried out with Factor H but in the absence of inhibitor; ns, not significant.