ANTI-ENZYME IMMUNITY 251 



conditions at 35° to 38 °C. through a regenerated porous porcelain 

 fiker. The preparation thus obtained had the following properties: It 

 dissolved egg albumin and fibrin, digested milk, liquefied gelatin, 

 hydrolyzed starch, (apparently contained a-amylase), and monobu- 

 tyrin, (apparently contained lipases). 



Inmiunization of Guinea Pigs. Adult guinea pigs were given 5 ml. 

 of enzyme extract intraperitoneally in small doses. During the next two 

 days they received 10 ml. each day in small doses. On the 4th day 

 they were given 2 ml. extract, and the injections were continued every 

 other day by increasing the volume by 2 ml. each time. On the 10th 

 day 10 ml. more of the extract was given. As stated by Achalme the 

 animal thus received twice the fatal dose. 



a. Antitryptic Property of Guinea Pig Serum Immunized with 

 "Trypsin." The enzyme preparation at a certain concentration exer- 

 cised a clotting effect on milk which might have been due to the pres- 

 ence of pepsin or chymotrypsin or both (Northrop 1939). The in- 

 hibitory action of immune sera on the milk clotting phenomenon by 

 the enzyme preparation was studied. The measurement of the clotting 

 of the milk was possible if the proteolytic activity of trypsin, which 

 immediately dissolved the clots formed, was inhibited by antitrypsin 

 immune serum. Preliminary experiments consisted of determining the 

 potency of the serum under various conditions. Achalme stated he 

 had convinced himself that normal or immune guinea pig serum, 

 collected under sterile conditions as soon as possible by separating 

 from the clotted blood, did not affect the milk. Fifteen drops of these 

 sera added to 5 ml. of milk after standing for 48 hours at 45 °C. 

 produced neither clotting nor digestion: pancreatin alone did not 

 clot the milk. At the most it produced a fine precipitate of casein 

 which dissolved immediately. In contrast, the addition of immune 

 serum produced a real massive clot followed by its dissolution. 

 However, in the presence of titrated amounts of trypsin and anti- 

 trypsin serum rapid clotting took place with the retardation of 

 incomplete dissolution of the clot after a prolonged period. 



The serum of a normal animal possessed only a weak antitryptic 

 activity in the above experiments. Achalme stated that even one volume 

 of normal serum is insufficient to neutralize the effect of one volume of 

 trypsin. In contrast one volume of immune serum neutralized the 

 activity of up to 8 volumes of trypsin solution. 



