Effects of cytotoxin-associated gene A (CagA) positive Helicobacter pylori infection on anti-platelet glycoprotein antibody producing B cells in patients with primary idiopathic thrombocytopenic purpura (ITP)

Objective: To explore the effects of cytotoxin-associated gene A (CagA) positive Helicobacter pylori (H. pylori or HP) infection on circulating B cells producing specific platelet glycoprotein antibodies and the association between therapeutic outcomes in primary idiopathic thrombocytopenic purpura (ITP) patients. Methods: A total of 76 newly diagnosed primary ITP patients were included in the study which was conducted at the first affiliated hospital of Shantou University Medical college, in Shantou city China, between January 2013 and January 2014. These patients were tested for H. pylori infection by 13C urea breath test and for anti-CagA antibody in H. pylori positive cases by enzyme-linked immunosorbent assay (ELISA) method. Anti-GPlb and anti-GPI lb/Illa antibody-producing B cells were measured using an enzymelinked immunospot (ELISPOT) assay in all ITP patients and 30 controls. Anti-nuclear antibody (ANA) was also detected in ITP patients. Results: The numbers of anti-GPIlb/Illa antibody-producing B cells in HP+CagA+ patients were higher than in HP+CagA- or HP- patients. However, anti-GPlb antibody-producing B cells were found higher in HPpatients. Analysis of treatment outcomes showed that a therapeutic response was more likely in patients presenting anti-GPI lb/Illa B cells, but the poor response was found to be associated with anti-GPlb B cells and ANA presences. Conclusion: CagA antigen of H. pylon may induce anti-GPIlb/Illa antibodies production by a molecular mimicry mechanism. Anti-GPIlb/Illa and anti-GPlb antibody producing B Cells detection is useful for predicting treatment effects of primary ITR