THE MAST CELL AND HEPARIN 



original source of heparin. Jorpes, Holmgren and Wilander (1937) extended 

 their investigations to various human tissues, again finding a satisfactory 

 correlation between mast-cell content and heparin value, and their findings 

 have been thoroughly endorsed by later work (Ehrich et al, 1949). The mast 

 cell-heparin hypothesis was confirmed some ten years later when a small mast- 

 cell tumour from the skin of a dog was found to contain fifty times more heparin 

 than the animal's whole liver, the organ from which 'heparin' received its 

 name (Oliver et al, 1947). Even the metachromatic granules of the blood 

 mast cells are believed to contain heparin (Behrens and Taubert, 1952; Martin 

 and Roka, 1953). As Jorpes (1946, p. 60) remarks, 'There is no doubt whatso- 

 ever about the nature of the granular substance of the mast cells. It is heparin.' 



According to Quensel (1933) mast cells are especially common around 

 thin-walled blood vessels and capillaries. Thus the new hypothesis seemed to 

 offer an attractive explanation for the well-known perivascular distribution 

 of the mast cells: mast cells are perivascular because they produce an anti- 

 coagulant which they pour into the circulating blood. Even to those with 

 little taste for teleology it seemed that Ehrlich's 'riddle' had been solved. 



The establishment of the mast cell-heparin hypothesis ended the second 

 phase of interest in the mast cells. The first, as we have seen, was their discovery 

 by Ehrlich and the evidence of later workers which appeared to relate the mast 

 cells to the connective tissues. The second phase gave the mast cell its first 

 physiological function; this seemed clearly to relate the mast cell to the blood. 

 It is the purpose of the next section of this book to describe the work of my 

 colleagues and myself in Scotland who have shown that the mast cell is not 

 only rich in heparin, it is equally rich in histamine. This has again directed 

 our thoughts towards a possible function of the mast cells in the tissues. 

 Inevitably it has also raised doubts concerning the functional significance of 

 the metachromatic substance of the mast-cell granules. 



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