Local immune response to repeated topical antigen application in the simian labial mucosa

Minor salivary glands of the oral mucosa in healthy monkeys (Macaca fascicularis and Macaca mulatta) contain organized structural units suitable for recognizing and processing antigens. A previous study of M. fascicularis monkeys provided experimental evidence of retrograde access of oral antigens deep into the minor salivary glands. The present study aimed at exploring the possible immune response of simian oral mucosa to repeated topical application of a chemically defined antigenic solution at the labial and gut mucosa. Ten female M. fascicularis animals were challenged topically at the lower lip mucosa at weekly intervals for a variable period of 4 to 8 weeks with a solution consisting of horseradish peroxidase, ferritin, and special India ink. Transmission electron microscopic examination of immunohistochemically treated sections of the labial glands revealed the presence of plasma cells containing specific anti-horseradish peroxidase antibody. These cells resided in the interacinar regions. Enteric and gut priming with the same antigen in four other monkeys, bypassing the oral mucosa, failed to reveal the presence of horseradish peroxidase-positive plasma cells in the labial mucosa of any of the four animals, although in one animal such cells could be identified in a mesenteric lymph node. This is suggestive of the existence, at least in primates, of a local immune response of the oral mucosa independent of systemic involvement.