Participation of the intestinal epithelium and mast cells in local mucosal immune responses in commercial poultry.

The intestinal mucosa of commercial poultry is continually subjected to invasion or colonization by a wide array of potentially hostile enteric pathogens. Although, recent investigations have focused on lymphocyte involvement in immune responses in the intestine, lymphocyte-mediated immunity alone will not explain the barrier nature of mucosal membranes associated with rejection of many enteric pathogens upon secondary homologous challenge. Our laboratories have focused on nontraditional elements of mucosal immunity in poultry to better understand host-pathogen interactions in the intestine. Following classical and novel immunization procedures, we have identified an antigen-specific mechanism of immediate responsiveness of the mucosal epithelium characterized by epithelial chloride secretion. This mechanism, characteristic of intestinal anaphylaxis, is mediated by local immune elements. Similar mechanisms in mammals contribute to the barrier nature of mucosal membranes during pathogen challenge. To identify cells participating in these and similar responses, additional studies have described a role for mast cells in acute phase responses in the intestines of chickens experimentally challenged with Eimeria. To a more practical end, other experiments in our laboratories have characterized drinking water administration of BSA for elicitation of local and systemic antibody responses. These experiments have shown ad libitum drinking water administration of BSA to be as effective as i.p. administration of BSA; they present a novel approach to immunization of commercial poultry with protein vaccines. These investigations support continued research on host-pathogen interactions within the intestine of commercial poultry to better understand and control enteric pathogens through vaccination or immunomodulation.