Major histocompatibility complex class I expression in human tonsillar and laryngeal epithelium

Area of Science:

• Immunology
• Otorhinolaryngology
• Oncology

Background:

• Understanding upper aerodigestive tract immunity is crucial for analyzing challenges like HPV infection and head and neck cancer.
• Previous studies indicated reduced human leucocyte antigen (HLA)-DQ expression in tonsillar and laryngeal epithelium compared to HLA-DR.
• This reduction may limit the presentation of T cell epitopes from exogenous peptides in airway mucosa.

Purpose of the Study:

• To investigate variations in the peptide repertoire presented by major histocompatibility complex (MHC) class I loci within stratified squamous epithelium.
• To compare MHC class I expression in laryngeal and tonsillar epithelium.

Main Methods:

• Quantitative immunofluorescence microscopy was performed on laryngeal and tonsillar biopsies from 19 patients.
• Antibodies targeting MHC class I alpha-chain (HLA-A, HLA-B + C) and beta(2)-microglobulin were utilized.
• Expression levels were quantified and compared between epithelial layers and tissue sites.

Main Results:

• MHC class I alpha-chain expression was lower in both laryngeal and tonsillar epithelium compared to lamina propria.
• Within the epithelium, expression intensity decreased from basal to apical layers.
• Tonsillar epithelium showed significantly higher alpha-chain expression than laryngeal epithelium.

Conclusions:

• Findings suggest functional stratification of upper airway epithelia, with the superficial layer less equipped for antigen presentation.
• This may impact immunosurveillance against viral and tumor-related epitopes in the upper airway.
• Reduced MHC class I expression in the superficial epithelium could influence head and neck cancer development and progression.