Mucosal inflammation in allergic rhinitis

In this investigation several studies were performed to determine the cellular and mediator events underlying disease expression. These studies were performed on samples from seasonal allergic rhinitics (SAR) and perennial allergic rhinitics (PAR) and were compared to those from normal non-rhinitics (NNR).Using resin immunohistochemistry (IHC) the numbers of MC and EO in AR were investigated. In the nasal mucosa of NNR no EO were observed either in the submucosa or epithelium, MC were seen in the submucosa only. SAR, when the grass pollen counts were high, was characterised by a migration of MC towards the epithelial surface of the mucosa and by an increase in the numbers of EO both in the submucosa and epithelium. When pollen counts were low changes were not observed. In PAR the level of inflammation was less than in SAR. EO were seen in the submucosa but there were no MC or EO in the epithelium.When examined ultrastructurally the MC and EO seen in the mucosa of all subject groups exhibited a range of morphological activation states which could not be attributed to any one disease group. A study of the mediators of AR, however, indicated that the MC and EO in SAR were activated. Increases in the levels of tryptase and eosinophil cationic protein were observed during the hayfever season. This was accompanied by an increase in total protein and albumin suggesting increased plasma leakage and vascular permeability. These same changes were observed in PAR compared to NNR.Changes in cell numbers and mediator levels can induce changes in the epithelium. Investigation of the intactness of the epithelium showed that in NNR a greater amount of epithelium consisted of basal cells only than in the AR groups and in SAR more epithelium consisted of basement membrane only than in the NNR.