Histochemical and immunohistochemical study of the mucosal lymphoid system in swine

Abstract

Summary Enzyme histochemical and immunohistochemical techniques were used to examine palatine tonsils and aggregated lymphoid follicles (Peyer's patches) of the ileum in 6- to 9-day-old and in 6-month-old pigs. Histochemical techniques were used to detect α-naphthyl-acetate esterase (anae), α-naphthyl-butyrate esterase (anbe), β-glucuronidase, adenosine triphosphatase (ATPase), and acid phosphatase (AcP). Nonspecific esterases (anae, anbe) were detected in macrophages, T-cell area lymphocytes, eosinophils, fibroblastic reticular cells (frc), follicular dendritic cells (fdc), and interdigitating cells (idc). β-Glucuronidase reactivity was strong in macrophages, eosinophils, fdc, and idc, and weaker in frc. Adenosine triphosphatase reactivity was detected in B-cell area lymphocytes, fdc, frc, and idc. Cell types with acid phosphatase reactivity were macrophages, fdc, frc, and idc. Nonepithelial cells of tonsils and aggregated lymphoid follicles of the ileum had similar enzymatic reactions. In Peyer's patches, however, epithelial cells were positive for all enzymes studied; in tonsils, only nonspecific esterases were detected. Immunoperoxidase techniques were used to detect S-100 protein and cytoplasmic immunoglobulins (IgG, IgM, and IgA). The S-100 protein was detected in lymphocytes, fdc, and frc of tonsils and Peyer's patches; in tonsillar epithelial and endothelial cells; and in idc of Peyer's patches. Cytoplasmic immunoglobulins were detected in lymphoblastoid and plasmacytoid cells of follicles and diffuse lymphoid tissue in both organs and in ileal epithelial cells. Compared with those of 6-month-old pigs, cells of 6- to 9-day-old pigs stained less intensely by all enzyme histochemical techniques, and fewer cells were reactive for immunoglobulins.