Human Mast Cells in the Allergic Nasal Mucosa

Abstract

The human mast cells in the allergic nasal mucosa contained many granules with various features. On the basis of electron microscopic observations, we have classified these granules into two groups: “normal” and “altered”. The former group consisted of granules which showed comparable structure to those in the normal environment. They contained electron dense, homogeneous material or less dense amorphous material. Many of them were surrounded only by a unit membrane, but sometimes a very thin envelope of the matrix was discernible immediately inside the unit membrane. The latter group comprised granules with marked ultrastructural changes. The swelling of the granules showing a clear halo formation around the matrix was a common feature. The internal substance obviously lost its electron density and became fibrillar or granular in appearance. These “altered” granules were fairly predominant in number as compared with those with “normal” structure. The ultrastructural changes found in the present study was quite smilar to those observed in the experimental degranulation studies caused by compound 48/80. Therefore, it seems reasonable to expect that mast cell granules of the allergic nasal mucosa are also released from the cytoplasm, responding to the antigenantibody reaction.