ANTIGEN-PRESENTING CELLS IN THE NASAL-MUCOSA OF PATIENTS WITH ALLERGIC RHINITIS DURING ALLERGEN PROVOCATION

Background The role of antigen presenting cells (APC) in allergic rhin itis is underexposed. Allergen presentation to T lymphocytes is probab ly an important aspect of the pathophysiological mechanism of allergic rhinitis. Objectives The aim of the study was to investigate the pres ence and dynamics of APC with special emphasis on Langerhans cells (LC ) in the nasal mucosa of patients with an isolated grass pollen allerg y during an out-of-season 2-week allergen exposure, mimicking the natu ral grass pollen season. Methods Seventeen patients with isolated gras s pollen allergy and four control subjects were challenged daily with allergen during a 2-week period in the winter. Biopsy specimens were o btained once before, six times during and once after the provocation p eriod. Biopsy sections were stained with monoclonal antibodies: OKT6 ( CD1a-Langerhans cells), Ki-M6 (CD68-macrophages), L25 (dendritic cells ), anti-IgE, HLA-DR and HLA-DQ (Major Histocompatibility Complex Class II - antigen presenting cells), as well as staining with acid phospha tase. Results APC with different characteristics are present in the ep ithelium and lamina propria of the nasal mucosa. The number of LC incr eased significantly in epithelium and lamina propria. IgE(+)-LC were p resent in the nasal mucosa and increase during provocation. HLA-DR(+) cells with dendritic and lymphocytic morphology and HLA-DQ(+) cells we re found. The number of these cells increased during provocation in ep ithelium and lamina propria. The number of HLA-DR(+) epithelial cells did not change. A significant increase in the number of Ki-M6(+) cells (macrophages) was found in the lamina propria. However, Ki-M6(+) cell s increased to the same extent in the lamina propria in the control gr oup. Conclusion APC are influenced by allergen provocation. This study supports the hypothesis that (IgE(+)) LC are involved in allergic rhi nitis. The role macrophages play remains doubtful.