THE MAST CELLS 



phosphatidic acids and their identification in biological material. Various 

 tissues, rich in mast cells, have been sent to Dr. Dawson, either in 1 : 1 chloro- 

 form/methanol or after preliminary hydrolysis, and he has chromatographed 

 them against known standards (Dawson, 1957). A special effort was made to 

 obtain a reasonably pure sample of isolated mast-cell granules from the rat 

 by taking advantage of the fact that the granules in this species are remarkably 

 resistant to the lytic action of water (Paff and Mergenthaler, 1955). 



Ten adult Wistar rats were killed by a blow on the head, skinned, and the 

 subcutaneous connective tissue was vigorously scraped off with a scalpel. 

 Representative samples of this were made into tissue spreads and stained with 

 toluidine blue and the remainder was then immersed in a stoppered bottle of 

 water and agitated at maximum speed for one hour in a mechanical shaker. 

 Tissue spreads prepared from the residue showed that a high proportion of the 

 mast cells had been disrupted and their granules scattered (Figs. 49 and 50). 

 The rest of the tissue pulp was strained through glass wool and the turbid 

 filtrate centrifuged. Examination of a smear of this deposit stained with 

 toluidine blue on a microscope slide, disclosed that it consisted mainly of mast 

 granules with a few nuclei. Chromatography of a hydrolyzed sample indicated 

 that the mast granules of the rat contain lecithin (phosphatidyl choline) and 

 phosphatidyl ethanolamine and are curiously rich in phosphatidyl serine, a 

 phosphatide which Kirschner (1957) has recently suggested may participate 

 in active sodium transport across the erythrocyte membrane. Other mast cell- 

 rich tissues which we have so far examined for phospholipids include portions 

 of a mouse mastocytoma (obtained through the kindness of Dr. Jacob Furth, 

 in Boston) and a specimen, believed to be a mastocytoma, from a cow. All 

 were found to contain phosphatidyl choline and appreciable amounts of phos- 

 phatidyl serine, though in somewhat lower concentration than in mast granules 

 isolated from the connective tissue of rats. 



Conclusions regarding the binding of histamine in the mast cell 



All the above observations are compatible with the belief, previously 

 expressed in this book, that the older views on 'bound' and 'free' histamine 

 are no longer tenable now that the intra-cellular location of tissue histamine 

 in the mast cell is known, and the site of its binding can be more critically 

 examined. The present work suggests strongly that much of the histamine 

 in a tissue is present in its mast cells, preformed and ready for release by any 

 agent which will disrupt the mast cell (water, alkali, trauma) or, more subtly, by 

 the somewhat heterogeneous group of 'histamine-liberators'. Very recently 

 Archer (1958) has described an endogenous histamine-liberator which may play 

 a vital role in the release of histamine in the inflammatory process. Knowledge 



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