Antigen presentation in the murine oral epithelium

Area of Science:

• Immunology
• Oral Mucosal Immunity
• Cellular Immunology

Background:

• The buccal mucosa's capacity to support delayed type hypersensitivity (DTH) reactions was previously established.
• Understanding antigen presentation within the oral mucosa is key to deciphering immune responses in this tissue.

Purpose of the Study:

• To investigate the antigen-presenting capabilities of cells within the buccal epithelium.
• To identify the characteristics and kinetics of antigen-presenting cells (APCs) in the oral mucosa.

Main Methods:

• Enzymatic dispersion of buccal epithelial sheets to isolate single cells.
• Presentation of native protein antigen hen-egg lysozyme (HEL) to specific T-cell hybridomas.
• Immunohistochemical staining for MHC class II and ATPase activity.
• Ex vivo T-cell activation assays using buccal epithelial cells (BECs) after in vivo antigen administration.
• Kinetic analysis of APC activity in buccal epithelium and draining lymph nodes.

Main Results:

• Buccal epithelial cells effectively presented soluble antigens to specific T cells, inducing interleukin-2 (IL-2) production.
• MHC class II-positive cells in the buccal epithelium exhibited dendritic morphology and ATPase activity, identifying them as APCs.
• BECs demonstrated rapid antigen uptake and presentation kinetics, peaking within 1 hour post-administration.
• Draining lymph nodes showed delayed APC activity, appearing 3-24 hours after antigen exposure.

Conclusions:

• Dendritic cells in the buccal epithelium function as potent APCs, acquiring antigens locally.
• These APCs migrate to draining lymph nodes to present processed antigens, initiating T-cell responses.
• This mechanism is critical for initiating Th1-driven DTH responses in the oral mucosa.