The T cells in peripheral taste tissue of healthy human adults: predominant memory T cells and Th-1 cells.

A healthy taste system is important to the maintenance of nutrition and overall quality of life, and taste disorders are associated with many inflammatory states. We previously determined the immune cells in normal human gustatory tissue; they are predominantly dendritic cells and CD4 T cells with a few macrophages and B lymphocytes present. There are, however, few reports of the subtypes of resident lymphocytes in or near taste tissues. The present study further characterized the distribution and population of the major subtypes of T cells in situ within biopsies of healthy human fungiform papillae (FP). Immunohistochemical analyses indicated that T-helper (Th)1 cells (CCR5+) were more predominant in FP than Th2 T cells (CCR4+). CD45RO+ memory T cells were the principal T cells in gustatory tissue, whereas CD45RA+ naive T cells were uncommon. Regarding subcompartments of the tissue, most intraepithelial lymphocytes of FPs were gamma/delta T cells, whereas the major subtype of lymphocytes in the lamina propria were alpha/beta T cells. Regulatory T cells that express CTLA-4 (CD152) and interleukin-2 receptors (IL-2R, CD25) were found at low levels in FP. The T cells stand ready to respond to inflammatory and infectious insults and may play a role in the taste alterations observed during acute and chronic inflammatory states.

Sour ageusia in two individuals implicates ion channels of the ASIC and PKD families in human sour taste perception at the anterior tongue.

BACKGROUND: The perception of sour taste in humans is incompletely understood at the receptor cell level. We report here on two patients with an acquired sour ageusia. Each patient was unresponsive to sour stimuli, but both showed normal responses to bitter, sweet, and salty stimuli. METHODS AND FINDINGS: Lingual fungiform papillae, containing taste cells, were obtained by biopsy from the two patients, and from three sour-normal individuals, and analyzed by RT-PCR. The following transcripts were undetectable in the patients, even after 50 cycles of amplification, but readily detectable in the sour-normal subjects: acid sensing ion channels (ASICs) 1a, 1beta, 2a, 2b, and 3; and polycystic kidney disease (PKD) channels PKD1L3 and PKD2L1. Patients and sour-normals expressed the taste-related phospholipase C-beta2, the delta-subunit of epithelial sodium channel (ENaC) and the bitter receptor T2R14, as well as beta-actin. Genomic analysis of one patient, using buccal tissue, did not show absence of the genes for ASIC1a and PKD2L1. Immunohistochemistry of fungiform papillae from sour-normal subjects revealed labeling of taste bud cells by antibodies to ASICs 1a and 1beta, PKD2L1, phospholipase C-beta2, and delta-ENaC. An antibody to PKD1L3 labeled tissue outside taste bud cells. CONCLUSIONS: These data suggest a role for ASICs and PKDs in human sour perception. This is the first report of sour ageusia in humans, and the very existence of such individuals ("natural knockouts") suggests a cell lineage for sour that is independent of the other taste modalities.

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

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.

Mesenchymoma: an unusual tumour of the lip.

The purpose of this paper is to present a case report of a benign mesenchymoma involving the lip. A brief review of relevant literature is presented.

Analysis of a human fungiform papillae cDNA library and identification of taste-related genes.

Various genes related to early events in human gustation have recently been discovered, yet a thorough understanding of taste transduction is hampered by gaps in our knowledge of the signaling chain. As a first step toward gaining additional insight, the expression specificity of genes in human taste tissue needs to be determined. To this end, a fungiform papillae cDNA library has been generated and analyzed. For validation of the library, taste-related gene probes were used to detect known molecules. Subsequently, DNA sequence analysis was performed to identify further candidates. Of 987 clones sequenced, clustering results in 288 contigs. Comparison of these contigs with genomic databases reveals that 207 contigs (71.9%) match known genes, 16 (5.6%) match hypothetical genes, eight (2.8%) match repetitive sequences and 57 (19.8%) have no or low similarity to annotated genes. The results indicate that despite a high level of redundancy, this human fungiform cDNA library contains specific taste markers and is valuable for investigation of both known and novel taste-related genes.