A MORPHOLOGICAL-STUDY OF THE LYMPHOCYTE TRAFFIC IN PEYERS-PATCHES AFTER AN IN-VIVO ANTIGENIC-STIMULATION

Background: Lymphoid cells have often been observed in the intestinal lumen and it has been hypothesized that M cells could represent one of the most important migration routes for the immunocompetent cells fro m the lymphoid follicle to the lumen. However, a direct evidence of th e passage was lacking. In this study we describe a morphological analy sis of the lymphocyte traffic in rabbit Peyer's patches after an in vi vo stimulation with an antigen normally not present in the intestine. Methods: The antigenic stimulation of a large number of Peyer's patche s was carried out using the isolated heal loop technique and then the samples from stimulated and control Peyer's patches were analysed by l ight and transmission electron microscopy. Results: We have been able to describe details of lymphocyte migration through M cells, from the follicle to the intestinal lumen, and a marked increase of intralumina l lymphocytes by counting the immunocompetent cells after periods of a ntigenic stimulation of varying lengths. Conclusions: Our finding is t hat the passage of lymphocytes to the lumen is an antigen-dependent ev ent and we also provide direct evidence that M cells are one of the mi gration routes. Our observations also indicate that lymphoid cells in the intestinal lumen may play an immunologic role in mucosal immunity. (C) 1994 Wiley-Liss, Inc.