Mucosal defense against enteric pathogens

Abstract

From the moment of birth the human gastrointestinal tract is assaulted daily with microorganisms; the lower ileum and colon are permanently and heavily colonized by bacterial flora. Man lives in a grossly contaminated world and has, therefore, had to adapt to survival in the midst of this contamination. Once organisms are swallowed the occurrence of a diarrheal episode depends upon the pathogenic potential of the agent, the inoculum ingested and the status of the host defense factors. Host defense factors can be divided into those operating nonspecifically against a broad range of agents and those with an immunologic basis directed against component of a specific microbe to which the host has been exposed previously.