Major differences in the IgG subclass response to Helicobacter pylori in the First and Third worlds

Background: Studies in developed countries would suggest that the immune response to Helicobacter pylori infection is a T helper cell 1 predominant response. Unlike subjects from developed countries, those resident in developing countries are subject to infection with a myriad of gastrointestinal pathogens from early in life. Given that H. pylori is acquired early in life, such infections may alter the immune response to H. pylori. The aim of this study was to compare the immune response to H. pylori in subjects from developed and developing countries. Methods: Using a previously validated IgG subclass ELISA, the H. pylori specific IgG1/IgG2 subclass ratio (a marker of the T helper cell response) in 58 adult and 21 paediatric symptomatic H. pylori positive Sowetan subjects was compared with that in 64 Australian and 45 German symptomatic H. pylori positive subjects. Results: An IgG1 predominant response (IgG1/IgG2 ratio > 1) was observed in 81% of Sowetan adults and 90% of children compared with 4.7% of Australians and 4.4% of Germans. The IgG1/IgG2 ratio was significantly higher in Sowetans compared with Australians and Germans (P < 0.001). In Australian and German subjects the IgG1/IgG2 ratio was significantly higher in NUD compared with DU. No significant difference was observed between NUD and other disease states in Sowetans. Conclusions: This study is the first to provide evidence that the host immune response to H. pylori infection in an African population differs to that observed in subjects from developed countries. Further studies are required to determine if this occurs in other developing countries.