Non-lymphoid cells of bronchus-associated lymphoid tissue of the rat in situ and in suspension

Abstract

Immunohistochemical, enzyme-histochemical and electron-microscopical methods were used to study non-lymphoid cells of control and stimulated rat bronchus associated lymphoid tissue (BALT) in situ and in suspensions. Particular attention was paid to the so-called antigen-handling cells, i.e., the interdigitating cells (IDC), which are situated in the T-cell areas, the follicular dendritic cells (FDC), which appear to be restricted to germinal centers, and macrophages, present both in T-cell and B-cell areas. The interdigitating cells were distinguished by being Ia-positive and by the presence of acid phosphatase and non-specific esterase activity in an area near the nucleus. Follicular dendritic cells could be observed in situ by using a monoclonal antibody and by the in vitro trapping of HRP-anti-HRP complexes. Several types of macrophages were found. At the electron-microscopical level no well-developed IDC and FDC could be detected in control BALT. However, in BALT of lipopolysaccharide-stimulated and mycoplasma-infected rats, well-developed IDC and FDC were found. It can be concluded that IDC's and FDC's can be found in BALT.

M Cell in the Immune System of the Lung

“…Re cently, the presence of B-cells in the lym phoepithelium of Peyer's patches could be demonstrated [47], Apart from lympho cytes, macrophages and so-called dendrit ic cells are also found [14,43]. The latter type of cell seems to perform important functions of antigen presentation in the interaction with the lymphocytes [14,31]. It should be noted, however, that the mor phological findings differ considerably both between the species of animals inves tigated and also between BALT and gutassociated lymphoid tissue (GALT), rec ommending great caution as far as general conclusions regarding immunological functions are concerned.…”

“…Contrary to current opinion, they seem not to be exclusively T-lymphocytes. Re cently, the presence of B-cells in the lym phoepithelium of Peyer's patches could be demonstrated [47], Apart from lympho cytes, macrophages and so-called dendrit ic cells are also found [14,43]. The latter type of cell seems to perform important functions of antigen presentation in the interaction with the lymphocytes [14,31].…”

Rapid changes in shape and number of MHC class II expressing cells in rat airways after Mycoplasma pulmonis infection

“…The number continued to increase along with the 10-fold increase in thickness of the tracheal mucosa evident at 4 weeks. The accumulation of OX6-positive cells in the airway mucosa after M. pulmonis infection was accompanied by the accumulation of airway-associated lymphoid tissue [16,17].…”

“…The organisms attach to the luminal surface of the airway epithelium of rats and mice [12] and are not cleared from the airways despite strong cellular and humoral immune responses [11,[13][14][15]. The ongoing stimulus causes an influx of mononuclear cells, including DC, macrophages, and lymphocytes [15][16][17][18]. The development of mucosal lymphoid tissue is a prominent part of the remodeling of the airway mucosa, and is accompanied by epithelial cell and mucous gland hyperplasia, fibrosis, angiogenesis, and increased sensitivity of the newly formed blood vessels to the neuropeptide substance P [13,14,19,20].…”

“…Although some of these changes may occur after viral infection [20,21], M. pulmonis infection is unusual in that it causes life-long disease and, if untreated, can result in severe remodeling of the airway mucosa [22]. The role of DC and other MHC class II expressing cells in these changes is unknown [16,17], but is of interest because of the rapid cellular response after infection and the strong immunological component of mycoplasmal airway disease.…”