Lipopolysaccharide (LPS) regulation of the immune response: LPS influence on oral tolerance induction

Previous work has been directed to determine the environmental influence of bacterial endotoxin from the indigenous Gram-negative flora on gut-associated lymphoreticular tissue (GALT), e.g., Peyer's patches (PP) and the IgA response. In the present study, the authors have compared LPS responsive and nonresponsive mice for induction of systemic unresponsiveness to antigen given for prolonged periods by the oral route (oral tolerance). The results suggest that oral administration of a thymic-dependent antigen to LPS-responsive mice induced a T suppressor cell population that suppressed responses to systemically administered antigen. LPS-nonresponsive mice lack this T suppressor cell pathway and continually respond to oral and systemic administration of antigen.