RESUMO
The intestinal mucosa is exposed to a vast antigenic contact. Several antigen presenting cell (APCs) have been described within the gut associated lymphoid tissue (GALT) (Peyer's patches, lamina propria, mesenteric lymph nodes, muscular layer); however, this has been done almost exclusively in adult organisms. As there is no characterization of intestinal muscular layer's APCs during early neonate development we adapted the conventional technique used in adults, to the neonate intestine. We obtained the intestinal muscular layer from early neonates (days 0-3 upon birth) and from young mice (2 and 3 weeks after birth). A planar network of CD45(+), MHC-II(+), DEC-205(+) cells with irregular, some with prominent dendritic morphology was found at birth under basal physiological conditions, whereas Langerin(+) DCs appeared after two weeks. The variations seen in CD45(+), MHC-II(+) and DEC-205(+) cells along the early neonatal development, could be related to the new challenges by intestinal antigen exposure from the newborn diet (breast milk, solid food), and to important environmental changes (start walking, exploring the surroundings, etc). Our study reveals the presence of APCs in intestinal muscular layer at birth, and their subsequent changes in physiological, non-induced conditions, contributing basic information about these cells in the neonate intestinal immune system.