COMPOSITION OF PUS 269 



Normal serum, and probably also normal cells, contain antibodies for 

 the proteolytic enzymes of the leucocytes, and hence neutralization or 

 destruction of these antibodies must be an important factor in de- 

 termining the rate and amount of suppuration.*^ 



The influence of the antionzj^mos is well siiown by the rabh)it, with 

 serum rich in antienzymes and leucocytes poor in protease, so that 

 infections with pus cocci do not usually lead to the formation of liquid 

 pus (Opie). In man we see a similar relation, in that exudates rich 

 in serum do not suppurate because the enzymes are inhibited by the 

 serum; but if the excess of serum is removed suppuration may then 

 occur. With an excess of enzyme (i. e., leucocytes) the inhibiting 

 effect may also be overcome, and suppuration then begins. Variations 

 in the proportion of leucoprotease and serum antiprotease determine, 

 therefore, the occurrence of suppuration, and the inflammatorj'' re- 

 action is seen to be fundamentally the same as the humoral reactions 

 of immunity, in that in each case the essential process is the provision 

 of proteolytic enzymes to remove foreign or abnormal protein sub- 

 stances. In inflammation the proteolytic enzymes are brought in the 

 leucocytes, in humoral reactions the enzymes are present free in the 

 plasma. The antiproteases may be of the nature of lipoids, probably 

 with unsaturated fatty acids ( Jobling) . 



The proteolytic enzymes of the leucocytes and tissue-cells have 

 been previously considered in connection with the subject of autolysis 

 (Chap, iii), and it is necessary here only to call attention to the fact 

 that these enzymes are of at least two varieties: (1) Proteolytic 

 enzymes of the polymorphonuclear leucocytes, which act best in alka- 

 line mechum (Opie^"); (2) autolytic enzymes of the tissue-cells, which 

 act best in an acid medium or after a preliminary acidification (Hedin, 

 et al.). The mononuclear leucocytes contain, like the tissue-cells, 

 enzymes acting in an acid medium. The antienzymatic action of 

 serum is favored by an alkaline reaction, but is altogether lost in an 

 acid medium (Opie). 



Composition of Pus 



Because of its method of production, pus consists of the follow- 

 ing substances: (1) The constituents of the exuded blood plasma; 

 (2) the constituents of the leucocytes (and tissue-cells) that exist free 

 in the pus; (3) the products of digestion of the proteins of the leuco- 

 cytes and necrosed tissues. All analyses of pus that are recorded in 

 the literature are in harmony with the above statements. In general 

 the analyses consider pus as composed of two chief portions, the pus 

 corpuscles and the pus serum. As is to be expected, the composition 

 of pus-corpuscles is simply that of a large mass of leucocytes, which 



»9See Opie, Jour. Exper. Med., 1905 (7), IHG; 1907 (9). 207; Arch. Int. Med., 

 1910 (5), 541. 



90 Jour. Exper. Med., 1906 (8), 410. 



