Antigen handling in the gastrointestinal lamina propria

Enteric infections associated with bacteria, viruses and parasites are a world health problem accounting for at least one billion episodes of diarrhoea and up to 10 million deaths in the Third World each year. The widely held conclusion that responses which are protective in the gastrointestinal tract are best stimulated by mucosal presentation of antigen remains largely unchallenged. Despite this there are but a few effective mucosal vaccines. The mucosal immune system of the gastrointestinal tract is presented with a contrasting array of antigens, ranging from harmless dietary components to highly pathogenic organisms, and has evolved a battery of responses from which an appropriate response may be orchestrated. We have postulated that the microenvironment in which an antigen is processed and presented to the mucosal immune system may profoundly influence the nature of the response and the purpose of this review is discuss a possible role for the lamina propria in this process.