Figure 6

Lewis X and Y antigen profiling by immunoblotting. Samples of LPS isolated from parallel cultures grown in the absence (-) or presence (+) of 50 μg/ml cholesterol were resolved on 15% urea gels. Quantities loaded per lane, as μg of initial lysate protein, are given at the top of each lane. Following transfer, antigens were immunodetected with monoclonal antibodies specific for Lewis X (upper panel) or Lewis Y (lower panel). A representative example of each is shown. Side lanes contain prestained protein markers (M) or 400 ng of E. coli O111:B4 LPS. Antigenic signal appeared only in the O-chain regions of these H. pylori strains; blank areas have been cropped out accordingly. The immunoblots were independently replicated with several sample sets, and densitometry was used to quantitate antigen signal in each lane. Ratios for pairwise plus:minus cholesterol samples were calculated, and the mean ratios ± sem for (n) blots are given in blue. The null hypothesis that the ratio equals 1 was evaluated in a two-tailed Student t-test.