Immune cells of the human peripheral taste system: Dominant dendritic cells and CD4 T cells

Abstract

Taste loss or alterations can seriously impact health and quality of life due to the resulting negative influence on eating habits and nutrition. Infection and inflammation are thought to be some of the most common causes of taste perception disorders. Supporting this view, neuro-immune interactions in the peripheral gustatory system have been identified, underlying the importance of this tissue in mucosal immunity, but we have little understanding of how these interactions influence taste perception directly or indirectly. This limited understanding is evident by the lack of even a basic knowledge of the resident immune cell populations in or near taste tissues. The present study characterized the distribution and population of the major immune cells and their subsets in healthy human anterior, lingual, fungiform papillae (FP) using immunohistochemistry. Dendritic cells (DCs) were the predominant innate immune cells in this tissue, including four subtypes: CD11c+ DCs, DC-SIGN+ immature DCs, CD83+ mature DCs, and CD1a+ DCs (Langerhans cells). While most DCs were localized beneath the lamina propria and only moderately in the epithelium, CD1a + Langerhans cells were exclusively present within the epithelium and not in sub-strata. A small number of macrophages were observed. T lymphocytes were present throughout the FP with CD4+ T cells more prevalent than CD8+ T cells. Very few CD19+ B lymphocytes were detected. The results show that DCs, macrophages, and T lymphocytes are the constitutive guardians of human FP taste tissue, with DCs and CD4 T cells being dominant, while B lymphocytes are rare under normal, healthy conditions These observations provide a basic anatomical foundation for the immune response in the healthy human tongue as a basis for subsequent disease-related studies, but none of the present data indicate that the immune cell populations identified are, in fact, altered in individuals with abnormal taste perception.

Human Cytomegalovirus Infection of Langerhans-Type Dendritic Cells Does Not Require the Presence of the gH/gL/UL128-131A Complex and Is Blocked after Nuclear Deposition of Viral Genomes in Immature Cells

“…Langerhans-type DC (LC) account for the totality of innate immune cells residing in the epithelial layer of the oral mucosae, while other types of myeloid DC, displaying surface markers similar to dermal DC, reside in deeper layers, including the lamina propria and submucosa (19)(20)(21)(22). DC populations morphologically, immunohistochemically, and ultrastructurally identical to LC can be differentiated in vitro from CD34 ϩ hematopoietic progenitor cells (23)(24)(25)(26), while a type of DC considered by some to be analogous to dermal CD14 ϩ DC (25)(26)(27) and by others to be inflammatory cells distinct from resident, steady-state dermal DC (28,29) can be obtained from monocytes (monocyte-derived DC [MDDC]).…”

Neutrophil responses to injury or inflammation impair peripheral gustatory function

“…Taste receptor cells exist within a barrier epithelium exposed to mechanical damage and pathogens. Thus, neutrophil recruitment with subsequent modulation of gustatory function may be an ongoing event (Olmsted, 1921), though analyses of the human peripheral taste system have largely focused on lymphocytes and dendritic cells (Cruchley et al, 1989, Feng et al, 2009). While lingual LPS has effects in addition to neutrophil recruitment, complementary results in this study show that when neutrophils respond to either CT nerve injury or lingual inflammation, sodium taste function is altered in intact taste receptor cells.…”

Mucosal dendritic cell diversity in the gastrointestinal tract

“…CD11c + myeloid DCs and DC-SIGN + immature DCs are both found in the epithelium and LP, but mainly in the LP (Table 3). CD83 + mature DCs are found in both the epithelium and LP, while CD1a + LC DCs are found solely in the epithelium (Feng et al 2009). The study of DCs and immune cells in the tongue may also have relevance due to their possible contribution to taste dysfunction in patients who suffer from this disease.…”