Distribution of Immunocompetent Cells in Normal Nasal Mucosa: Comparisons among Germ-Free, Specific Pathogen-Free, and Conventional Mice

Abstract

To better understand the role of immunocompetent cells in the defense mechanism of the upper respiratory tract against microbial invasions, the distribution patterns of those cells were investigated in nasal mucosa of mice maintained in three different conditions: germ-free (GF), specific pathogen-free (SPF), and conventional (CV) conditions. Immunostaining by the indirect peroxidase method and toluidine blue staining were employed for the detection of immunocompetent cells and mast cells. For immunostaining, anti-IgG, -IgA, and -IgM polyclonal antibodies and anti-Lyt-1, -Lyt-2, and -Mac-1 monoclonal antibodies were used as primary antibodies. In nasal mucosa of CV mice, Mac-1+ cells, mast cells, and all cell types of lymphocyte subsets were present. In nasal mucosa of SPF mice, all cell types were also positive, but fewer in number than those of CV mice. In nasal mucosa of GF mice, IgG+, IgA+, and Lyt-2+ cells were rare, although IgM+ and Lyt-1+ cells were present in small numbers. An electron microscopic study revealed that follicle-like lymphocyte aggregates with high endothelial venules were present in nasal mucosa close to the mucosal epithelia. These findings suggest that lymphocytes are mobilized to nasal mucosa, responding to continuous antigenic stimuli, and play an important role in the local defense mechanism of the upper respiratory tract.

Effects of experimental Mycoplasma pulmonis infection on sensory neuropeptides and airway mucosa in the rat

“…In our uninfected GF animals, subepithelial lymphoid aggregations were scarce and appeared inactive. Similar findings have been reported in studies of the gastrointestinal canals of GF rats [31] and in the nasal mucosa of GF mice [32]. While the intestinal flora is important for the wellbeing of the host, it is doubtful whether the normal nasal flora is similarly beneficial.…”

Ultrastructural study on the follicle‐associated epithelium of nasal‐associated lymphoid tissue in specific pathogen‐free (SPF) and conventional environment‐adapted (SPF‐CV) rats

“…Previous reports have shown that immunocompetent cells in the nasal mucosa are fewer in number and immunologically less mature in germ-free (GF) and SPF animals than in CV animals (Ichimiya et al 1991), and the numbers of T and B cells in NALT are 2-3 times greater after an experimental infection (Asanuma et al 1997). In the present study, NALT had more numerous and well-developed follicles in SPF-CV rats than in age-matched SPF rats.…”

Kinetics of mouse antibody and lymphocyte responses during intranasal vaccination with a lipooligosaccharide-based conjugate vaccine

“…The gut-associated lymphoid tissues (GALT), the bronchus-associated lymphoid tissues (BALT), and the nasopharyngeal-associated lymphoid tissues (NALT) are part of the mucosal associated lymphoid tissues (MALT). The rodent NALT, which consists of paired lymphoid structures at the entrance of the nasopharyngeal duct, is considered to be the equivalent of Waldeyer's ring in humans [14][15][16] and has been shown to participate in the defense of respiratory tract and other mucosal sites [17,18]. The NALT is believed to serve as the mucosal inductive site for the upper respiratory tract and the nasal/oral cavity [15], and is important for inducing the mucosal immune responses after IN immunization [19,20].…”