Host determinants of Helicobacter pylori infection and its clinical outcome

Greater than one-half of the world's population harbors Helicobacter pylori . The majority of infected individuals, however, remain asymptomatic, with only 10% to 20% developing diseases, including peptic ulcer disease, gastri c cancer, and gastric mucosa-associated lymphoid tissue lymphoma. This arti cle reviews host factors that may predispose an individual to both the acqu isition of H. pylori infection and subsequent clinical outcome. Individuals with specific blood group antigens and human leukocyte antigen genotypes m ay be more susceptible to H. pylori infection. Additional factors, such as the age of acquisition, the host immune response, the site of infection, ac id secretion, and interactions with nonhost factors (including bacterial vi rulence factors and environmental influences) may play a role in determinin g clinical outcome. Further investigation is required to clarify the mechan isms by which these interactions occur and, more critically, to determine t heir relative importance. This knowledge will enable the identification of individuals at risk of developing clinical disease with H. pylori infection .