PROTEINASE CONTENT OF MAST-CELLS OF NASAL-MUCOSA - EFFECTS OF NATURALALLERGEN EXPOSURE AND OF LOCAL CORTICOSTEROID TREATMENT

The distribution and density of metachromatic cells (MCC) and mast cel ls containing chymase plus tryptase (MC(TC)) or tryptase alone (MC(T)) were studied in the nasal mucosa by dye-binding methods and immunohis tochemical analysis. Biopsies were obtained from 17 subjects with birc h pollen allergy before and during the peak season and from nine healt hy controls. Six patients were treated with an intranasal glucocortico steroid before and during the season in an open study. Hay fever patie nts, even when asymptomatic, showed signs of mast cell system activati on, exhibiting an increased number of mast cells in the nasal epitheli um. Basophils, lacking immunohistochemically detectable tryptase, were not a major component of the mast cell response. MC(T), most conspicu ous in the epithelium, were found to be the most frequent mast-cell ty pe in the nasal mucosa of allergic, but not of normal, subjects. Only 33% of the epithelial, but 90% of the stromal, immunopositive cells in the atopic mucosa before as well as during the season were MCC. Intra epithelial MC(T) thus displayed a low capacity to stain metachromatica lly, indicating a relative deficiency of the glycosaminoglycan (hepari n) component of the granules. Intraepithelial mast cells also appeared to be markedly sensitive to steroid treatment and aldehyde fixation. The findings suggest that the lack of chymase, the characteristic feat ure of MC(T), may reflect a functional activation of the mast cells, r ather than a stable phenotypic differentiation related to anatomic sit e.