LEUKINS AND LEUKOCYTIC EXTRACTS 361 



lymph, indicating that this activity takes place both in the test-tube 

 and in living tissues. 



Hiss, and later Hiss and Zinsser, found that autolyzed leukocytic 

 exudates possess some bactericidal activity, and that they may pro- 

 foundly modify experimentally induced infection of rabbits and guinea- 

 pigs with the pneumococcus, staphylococcus, streptococcus, and other 

 bacteria. In applying this method of treatment to man by means of 

 subcutaneous injections, these investigators observed distinctly bene- 

 ficial results in cases of epidemic cerebrospinal meningitis, lobar pneu- 

 monia, staphylococcus infections, and erysipelas. 



Preparation of Leukocytic Extracts. Hiss and Zinsser have pre- 

 pared leukocytic extract by giving rabbits intrapleural injections of 

 aleuronat suspension. Manwaring has secured much larger quantities 

 by making his injections into the horse. 



The aleuronat is prepared by making a 3 per cent, solution of starch 

 in bouillon without heating, and adding 5 per cent, of powdered aleuronat 

 to this emulsion. The starch helps to keep the aleuronat in suspension. 

 The mixture is boiled for five minutes and placed in large sterile test- 

 tubes, 20 c.c. being placed in each tube. Final sterilization is done in 

 an autoclave. 



For making the injections large rabbits are selected. The hair over 

 both sides of the thorax is removed, the skin is sterilized with tincture 

 of iodin, and 10 c.c. of the aleuronat suspension are injected into each 

 pleura! cavity at a point in the anterior axillary line, at the level of the 

 sternum, great care being taken to avoid puncturing the lungs. After 

 twenty-four hours the animals are chloroformed and the pleural cavities 

 carefully and aseptically opened. The cellular exudate is pipeted into 

 centrifuge tubes containing at least 10 c.c. of sterile 1 per cent, sodium 

 citrate in normal salt solution. One or more cubic centimeters of exu- 

 date may be obtained from each cavity. The exudate is usually tinged 

 with blood. It is then centrifuged and the supernatant fluid removed. 

 The sediment is broken up with a platinum spatula, and 20 volumes of 

 sterile distilled water are added. The tubes are set aside in the incuba- 

 tor for twenty-four hours, after which cultures are made to insure steril- 

 ity. A small amount of preservative may be added, and the extract 

 placed in bottles or ampules ready for administration. It is given sub- 

 cutaneously in doses of from 5 to 10 c.c. every four to six hours. 



The endocellular bactericidal substances, or endolysins, mentioned 

 in a previous chapter, which can be extracted from leukocytes, are not 

 in the nature of complements, as they are not rendered inactive by tern- 



