Heterogeneity of metachromatic cells in human nose: Significance of mucosal mast cells

The distribution and abundance of histochemically and morphologically distinct subpopulations of metachromatic cells were investigated in nasal secretions and scrapings from patients with allergic rhinitis, as well as in nasal biopsy specimens from other patients. These analyses of the metachromatic cells demonstrate that basophils and two distinct mast cell populations are present in nasal specimens. One mast cell subpopulation was analogous to the atypical mucosal mast cell of the rat and human intestine, whereas the other cell population was similar to the typical connective tissue mast cell type. In nasal scrapings greater than 80% of the metachromatic cells was mast cells, almost exclusively of the atypical "mucosal" type. However, basophils were the predominant metachromatic cell type in nasal secretions, and atypical mast cells were more abundant than typical mast cells. Few basophils were observed in biopsy specimens, but mast cells were widely distributed in various anatomic compartments. Atypical mast cells outnumbered the typical type in the epithelium and lamina propria, whereas the reverse was true in the submucosa. When the number and type of metachromatic cell in scrapings were analyzed in relation to clinical findings, there was a significant correlation with severity of symptomatology and nasal swelling and pallor. Atypical "mucosal" mast cells were the major cell type in all specimens, from those with mild to those with severe clinical findings. When the distinct spectrum of responsiveness to antiallergic compounds of atypical mast cells is considered, these observations have important therapeutic implications.