Long-term repeated daily use of intragastric gavage hinders induction of oral tolerance to ovalbumin in mice.

Oral tolerance is dependent on the complex architecture of the mucosal system of the gastrointestinal tract, its associated lymphoid tissue, and specialized immune cells. Changes in this architecture or the failure of any of its components may hinder the generation of oral tolerance. The larynx and esophagus are the gateway to the gastrointestinal tract, serving as the site of oral antigen introduction to the immune system and may have an important role in establishing tolerance. Intragastric gavage is a common method for precise oral dosing of rodents, particularly in studies examining oral tolerance. However, complications such as esophageal trauma can occur and induce complicating factors that affect experimental outcomes. In this study, we examined the esophageal epithelium for alterations resulting from long-term repeated daily use of intragrastric gavage and its effect on the induction of tolerance. Tolerance to ovalbumin could not be achieved after using intragastric gavage for 14 d or more consecutively to introduce ovalbumin. However, tolerance was achieved when intragastric gavage was used for shorter durations. After 14 d of gavage, disruption of the esophageal mucosal epithelium indicative of an inflammatory pathology, cellular influx into the esophageal tissue, and proinflammatory cytokines in the tissue were absent, and the CD3(+) cell population in the esophageal epithelium decreased. These findings provide initial evidence for the important roles of esophageal integrity and cellular populations in the induction of oral tolerance and suggest possible immunologic sequelae in experiments involving the use of extended, repeated gavage.