Lymphocyte subsets in porcine tonsillar crypt epithelium

The palatine tonsils are part of the mucosa-associated lymphoid tissue (MAL T), strategically located in the oropharynx at the entrance of respiratory and gastrointestinal tracts, and are recognized portals of entry and sites of multiplication and persistence of several pathogens in pigs. As the tons illar crypt epithelium is in close contact with external environment and th e underlying lymphoid tissue, the characterization of the intra-epithelial lymphocyte subpopulations is essential for the understanding of initial ste ps of pathogenesis of several diseases. In this work we investigated specif ic lymphocyte subsets in the tonsillar crypt epithelium of 10 adult healthy pigs, using monoclonal antibodies against lymphocyte markers CD3, CD4, CD8 , gamma delta T cell receptor and immunoglobulin light-chain in an avidin-b iotin immunoperoxidase technique. The crypt epithelium was usually extensiv ely infiltrated by a diverse population of T cells and by B cells. The degr ee of infiltration of each subset was variable among animals and within ind ividual animals. In the T cell population CD4 cells and gamma delta TCR cel ls predominated over CD8 cells. These data suggest that the crypt lymphoepi thelium is capable of participating in both cellular and humoral immune res ponses and that gamma delta T cells may play an important role in the defen se of this mucosa. (C) 2000 Elsevier Science B.V. All rights reserved.