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

Abstract

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.

Figure 1

Presence and distribution of CCR4+ (Th2) and CCR5+ (Th1) cells in the human FP. The brown color in the sections shows the specifically stained cells. (A) CCR5+ expressing Th1 cells. (B) CCR4+ expressing Th2 cells. The yellow dotted line shows taste bud. The scale bar indicates 20 μm.

Figure 2

Presence and distribution of CD25+ and CD152+ cells in the human FP. The brown color in the sections shows the specifically stained cells. (A) CD25+ expressing T cells. (B) CD152+ expressing T cells. The scale bar indicates 20 μm.

Figure 3

Presence and distribution of CD45RA+ (naive T cells) and CD45RO+ (memory T cells) in the human FP. The brown color in the sections shows the specifically stained cells. (A) CD45RA+ expression and distribution. (B) CD45RO+ expression and distribution. The yellow dotted line shows taste bud. The scale bar indicates 40 μm.

Figure 4

Presence and distribution of α/β T cells and γ/δ T cells in the human FP. The brown color in the sections shows the specifically stained cells. (A) α/β T cells. (B) γ/δ T cells. The yellow dotted line shows taste bud. The scale bar indicates 20 μm.

Figure 5

Presence and distribution of CD123+ PDCs in the FP. The brown color in the sections shows the specifically stained cells. (A) CD123+ DCs exclusively present in lamina propria, with few present in epithelial compartment. The scale bar indicates 20 μm. (B) High magnification of image showing that endothelial venules in FP tissues also express CD123. The scale bar indicates 10 μm.

Figure 6

Cellular populations in epithelium and lamina propria. The cell densities are presented as the percentages of specifically stained area against the total area of the histological section. Data are expressed as mean ± SE, n = 12, which is the number of subjects analyzed. EP, epithelium; LP, lamina propria; TCRa, α/β T cells; TCRg, γ/δ T cells.