92 ENZYMES 



AUTOLYSIS IN PATHOLOGICAL PROCESSES 



All absorption of dead or injured tissues, and of organic 

 foreign bodies, seems to be accomplished by means of digestion 

 by the enzymes of the cells and tissue fluids. We may distin- 

 guish between the digestion brought about by the enzymes of 

 the digested tissue itself, or autolysis, and digestion by enzymes 

 from other cells or tissue fluids, or heterolysis (Jacoby). Heterol- 

 ysis is accomplished particularly by the leucocytes, which 

 contain ferments capable of digesting not only leucocytic pro- 

 teids but apparently every other sort, 1 from serum-albumin to 

 catgut ligatures. The heterolysis may be intracellular when 

 the material to be digested has first been taken up by the cells 

 (phagocytosis) ; or extra-cellular, either by enzymes normally 

 contained in the blood plasma and tissue fluids, or by enzymes 

 liberated by the leucocytes and fixed tissue cells. On death 

 and dissolution of a cell the intracellular enzymes are released, 

 but it is not known to what extent the enzymes may be secreted 

 from intact living cells. As far as pathological processes show, 

 the amount of liberation of enzymes from normal cells is very 

 slight, if any, and the digestive enzymes of the blood plasma 

 seem to be very feeble, but this is perhaps because they are 

 largely held in check by the anti-enzymatic substances of the 

 serum. Pathological autolysis and heterolysis, therefore, are 

 brought about chiefly by enzymes liberated from dead or injured 

 cells. Bacteria, however, can multiply upon a medium of coagu- 

 lated proteid, which suggests that they also secrete proteolytic 

 substances, for otherwise it would be difficult to explain how 

 they secure their nourishment. In pathological conditions, 

 digestion of degenerated tissues seems usually to be the result 

 of both autolysis and heterolysis. An infarct softens because 

 the intracellular enzymes digest the dead cells, exactly as they 

 do when the tissue is removed from the body, ground up, and 

 put in the incubator under toluol. In addition leucocytes 

 wander in, disintegrate, and their liberated enzymes help in the 

 process, as also do to a less degree the enzymes of the blood 

 plasma. It is because of the heterolysis by leucocytic enzymes 

 that a septic infarct becomes softened so much more rapidly 



1 Many authors suggest that the leucocytes merely carry enzymes from one 

 organ, particularly the pancreas, to another, and that these enzymes are not 

 formed by the leucocyte itself. Opie (Jour. Exp. Med., 1905 (7), 759) has 

 shown, however, that the bone-marrow contains proteolytic enzymes which are 

 like those of the leucocytes in that they act best in an alkaline medium, 

 whereas the autolytic enzymes of the lymphatic glands and most other tissues 

 act best in an acid medium. This leaves little room for doubt that the leuco- 

 cytes are equipped with their characteristic enzymes when they leave the bone- 

 marrow, and that they are not obtained later in the pancreas or elswhere. 



