THE MAST-CELL GRANULE 



in the skin of both rat and mouse can convert 5-hydroxytryptophan into 

 5-hydroxytryptamine. The work of Riley and Drennan (1949), Friberg et al 

 (1951), Wislocki and Fawcett (1951), Compton (1952), Montagna et al (1946, 

 1948, 1954), Montagna (1957) and others have extended the histochemical 

 observations of Noback and Montagna (1946) on the complex structure and 

 enzyme content of the granules. Zollinger (1950), for example, has likened the 

 granules to 'giant mitochondria'. However, recent studies with the electron 

 microscope (Bloom and Friberg, 1953; Bloom et al, 1955; Smith and Lewis, 

 1955; Stoeckenius, 1956; Rogers, 1956) confirm that the mast cell usually 

 contains a few typical mitochondria in addition to its vast complement of large 

 granules (Nakajima, 1928). Indeed, recent biochemical evidence supports the 

 view that it is the large granule which contains the histamine (West, 1955), 

 heparin (Koksal, 1953) and 5-hydroxytryptamine (Barrnett et al, 1958). The 

 inter-relationship, if any, of the two types of cytoplasmic inclusion has yet to 

 be determined. Hence it is clear that the mast-cell granule is more than a mere 

 chemical polymerization of heparin, or even of heparin and histamine: it is a 

 metabolically active organelle which responds to changes in its environment 

 as an intracellular osmometer, and, acting in this way, is capable of liberating 

 its contents. 



Effect of trichloracetic acid (See West and Riley, 1954) 



Trichloracetic acid is so efficient, and acts so rapidly, in extracting histamine 

 from a tissue rich in mast cells that it seemed worth while to examine more 

 closely its mode of action. In the first place, the very fact that trichloracetic 

 acid is so efficient in withdrawing histamine from its depots, seriously impairs 

 any hypothesis that histamine must first be formed enzymatically from histidine 

 in protein before it can be released into the body fluids. Trichloracetic acid 

 precipitates protein and thus inhibits enzymic action; and the fact that water is 

 itself an efficient histamine-liberator adds further to the present belief that the 

 histamine already exists, preformed, in the mast cell, held only by loose ionic 

 linkages. 



In order to obtain information about the action of trichloracetic acid, 

 suitable tissue extracts were subjected to chromatographic analysis. 



Extracts of tissues exceptionally rich in histamine, such as ox pleura, ox 

 liver capsule, and mast-cell tumours from dogs, were prepared for ascending 

 chromatographic estimation of histamine by simple extraction or by grinding 

 the tissues with 10 per cent aqueous trichloracetic acid and centrifuging. Using 

 as solvent mixture «-butanol : acetic acid : water (4:1: 5), it was observed that 

 after spraying with the Pauly or the paranitraniline diazo-reagent not one, but 

 two, sharply defined spots appeared on the chromatogram of R F =0T1 and 

 0-65. Both spots contained material which when eluted with water or 0-01 



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