Preliminary evidence for 'aberrant' expression of the leukocyte integrin LFA-1 (CD11a/CD18) on conjunctival epithelial cells of patients with mite allergy.

BACKGROUND: We have previously shown aberrant expression of the 'leukocyte' integrin LFA-1 on epithelial cells in chronic autoimmune thyroiditis. In the present study we investigated whether conjunctival epithelial cells, which bear the adhesion molecule ICAM-1 on their surface during allergic inflammation, may also aberrantly express its natural ligand, the 'leukocyte' integrin LFA-1. METHODS: We studied 13 patients with rhinoconjunctivitis allergic to mites, chronically exposed to the allergen, 11 patients allergic to pollen tested out of the pollen season and 8 normal volunteers. Single and double immunocytochemical staining of conjunctival smears was employed. RESULTS: LFA-1 staining on epithelial cells was demonstrated in 12/13 patients allergic to mites and not in normal controls or in patients allergic to pollen tested out of the pollen season. The epithelial localization of LFA-1 was confirmed by double staining with anti-LFA-1 and anti-cytokeratin antibodies (both immunocytochemical and immunofluorescence). CONCLUSIONS: Coexpression of LFA-1 and ICAM-1 during persistent allergen stimulation may be relevant for interaction between epithelial cells and activated effector cells, such as eosinophils, which bear on their surface both ICAM-1 and its beta2 integrin ligands.

Nasal response to a single antigen challenge in patients with allergic rhinitis - inflammatory cell recruitment persists up to 48 hours.

BACKGROUND: Allergen challenge in some patients with respiratory allergy is followed by an early and a late reaction. OBJECTIVE: To evaluate the duration of mediator release and inflammatory cell recruitment during the late antigen-induced nasal response. METHODS: Eight patients with seasonal allergic rhinitis due to grass pollen underwent local challenge with the relevant allergen, a non-relevant allergen (Parietaria judaica), and nebulized saline solution. Nasal lavages were performed at baseline and 6, 24, 48, 72 h after challenge. Eosinophil cationic protein (ECP), leukotriene C4 (LTC4), leukotriene B4 (LTB4) myeloperoxidase (MPO) and prostaglandin D2 (PGD2) levels were radioimmunoassayed and histamine concentration was measured by an automated fluorometric method. RESULTS: Nasal challenge with the relevant antigen induced a response 6 h after stimulation, which subsided within 24 h. Eosinophilia, observed in the nasal lavages collected from 6 to 24 h after this challenge, was accompanied by ECP release. Neutrophilia were found in the nasal lavages collected from 6 to 24 h after challenge. The increase in neutrophil number correlated with MPO levels and LTB4 concentrations, but not with the intensity of nasal obstruction. Antigen challenge also induced significant recruitment of mononuclear cells 48 h after provocation. The challenge significantly raised histamine, but not PGD2, levels in the nasal lavages collected 6 h after provocation. A trend towards an increase in LTC4 levels in the nasal lavages collected 6 h after specific antigen challenge was also found. Nasal challenge with a non-relevant allergen or with saline solution did not cause either inflammatory cell recruitment or mediator release. CONCLUSION: Nasal challenge with the relevant antigen can induce a late response characterized by local accumulation of eosinophils, neutrophils and mononuclear cells persisting for 48 h and accompanied by release of ECP, MPO, LTB4 and histamine. These results indicate that a single antigen challenge in patients with allergic rhinitis causes prolonged inflammatory alterations which may contribute to the development of airway hyperreactivity.