Megraud F Clinical Microbiology Reviews Apr 2007, p.280-322

Detection of H. pylori Antibodies Serodiagnosis. H. pylori infection is a chronic condition and immunoglobulin G (IgG; subclasses 1 and 4) is the predominant immunoglobulin class even in children. IgG are present at the mucosal level and detected in virtually all blood samples. IgM are rarely observed merely because acute H pylori infections are seldom available for study. As the relevance of IgM and IgA is limited commercial kits are primarily designed to detect IgG. It is well known that IgG levels begin to decrease after eradication of H pylori but this fall in titer may take months or years before returning to baseline values. (Click here to view/order article at Pubmed)