Tryptase- and ghrelin positive mast cells in the interalveolar septa of rat’s lung

Abstract

The mast cell mediators and distribution of lung mast cells in rats are often discussed in experimental studies on pulmonary fibrotic and allergic processes associated with changes in numbers of these cells, but information on the normal distribution of metachromatic and tryptase-positive mast cells in the interalveolar septa is scarce. There are no data on the presence of ghrelin in lung mast cells as well as the age-specific features of localisation and the number of mast cells in the interalveolar septa in rats of different ages. Therefore, the purpose of the present study was to determine the distribution of metachromatic, tryptase-, and ghrelin-positive mast cells in the interalveolar septa in 20 day-, 3 month- and 1 year-old rats. Tissue sections stained with toluidine blue had been taken from the left lung to visualise metachromasia and immunohistochemical expression of tryptase and ghrelin. The results showed that the amount of metachromatic mast cells in the interalveolar septa was significantly lower than that of tryptase- and ghrelin-positive cells. This allowed suggesting that mast cells were permanent occupants of the rat lung parenchyma and, on the other hand, the expression of ghrelin in their granules was most likely related to the synthesis of this protein. Our study showed that immunohistochemical identification by tryptase expression was more accurate than toluidine blue staining.