Localization by immunofluorescence of secretory component and IgA in the intestinal mucosa of the young pig.

The cellular distribution of IgA and secretory component in porcine intestinal mucosa has been studied by immunofluorescence. Secretory component was localized in crypt epithelium of all animals examined. It was also demonstrated in goblet cells on the villi of colostrum-fed neonates and of older animals, both colostrum-deprived and conventionally suckled, and in the crypt epithelial cells of an 80-day-old foetus and of colostrum-deprived new born animals. Sequential biopsy studies on a young fistulated animal demonstrated that the onset of active secretion of intestinal IgA did not occur before the second week of life. The significance of these findings is discussed in relation to the synthesis and transport of IgA.