32 THE PRINCIPLES OF IMMUNOLOGY 



pointed out, however, that phagocytosis is not the only way in 

 which an increase of leucocytes may operate beneficially. The 

 studies of Hiss and Zinsser indicate that extracts of leucocytes have 

 a beneficial effect on infections and others have confirmed these 

 results. Bail claims that a fresh emulsion of leucocytes will aid in 

 neutralization by the specific anti-serum of endotoxin obtained from 

 cholera vibrios. Jobling and Bull, however, demonstrated that leu- 

 coprotease " will destroy the toxic extracts of typhoid bacilli and 

 meningococci, and it is not improbable that a similar explanation 

 will apply to the results obtained by Bail." 



There are other possible changes in the blood as the result of the 

 injection of protein. The work of Jobling and his collaborators has 

 thrown great light on the alterations of ferments and anti-ferments 

 in the blood under a wide variety of conditions. The injection of 

 various substances is almost invariably followed by a considerable 

 mobilization of the serum ferments, more particularly the protease, 

 and usually also the esterase. The value of the protease is probably 

 in the direction of breaking down toxic split-protein products, which 

 probably originate during the course of infectious disease, as the 

 result of the splitting of bacteria and perhaps also of the body pro- 

 teins. Protease does not act directly upon living bacteria, but it is 

 to be considered possible that the esterase may break up the lipoid 

 or lipoid-protein surface of the bacteria and therefore aid in their 

 destruction. If we concede that the toxic protein split products aid 

 in the virulence of bacteria it is possible that even although the 

 protease simply breaks down these products into simpler non-toxic 

 substances and does not directly attack the bacteria, yet the relief to 

 the body afforded by this detoxifying action may assist it more 

 permanently in combating disease. In certain states, such as preg- 

 nancy, in disease such as cancer, and in the course of vaccine treat- 

 ment the anti-ferment titer of the blood has been found to be high. 

 Jobling and Peterson found that the anti-ferment power of the blood 

 depends upon the amount of unsaturated lipoids present in highly 

 dispersed phase in the serum and Bogolemez suggests that lipoids 

 may serve to inhibit toxins, as is true in relation to the toxin of 

 bacillus botulinus. Anti-ferment is not increased following protein 

 injections and plays no part in the non-specific therapy of infectious 

 disease, but inasmuch as the change may be seen in immune states, 

 such as that following vaccination, it may be of importance in non- 

 specific resistance to infection. In addition to the changes in fer- 

 ments Jobling has found that the injection of non-specific proteins 

 may produce changes in the viscosity of the serum. It is known 

 that if precipitates are formed in serum by the action of a specific 

 precipitating serum, conditions favorable to protease activity are 

 produced and the changes in viscosity produced by protein injec- 

 tions may similarly aid proteolytic activity. These changes in 

 ferment content and physical character of the serum are of short dura- 

 tion and are probably contemporaneous with the chill and fever. 



