Figure 4.

IgA1 protease activity of H. pylori strains examined by immunoelectrophoresis with polyclonal antibody against the Fc portion of IgA. Well a shows negative control, ie, intact IgA1 preparation without bacteria; well b shows positive control, ie, IgA1 preparation after incubation with H. influenzae strain producing IgA1-specific protease (note cleaved fragment, arrowhead). Remaining wells (c–e) show IgA1 incubated with representative isolates of H. pylori (note no evidence of IgA cleavage products). Anode is at the top.