PRODUCTION OF HEMOLYSINS 71 



Milk Precipitins (Lactoserums). These are prepared by immuniz- 

 ing large rabbits with intravenous or intraperitoneal injections of milk, 

 that of either the human or the lower animals. Rabbits should be im- 

 munized with at least two kinds of milk in order to obtain different 

 lactoserums for the study of specificity. The milk used for the injec- 

 tions should be as sterile as possible, and if heated to 56 C. for one-half 

 hour before the injections are made, the protein remains unchanged and 

 the rabbits are less likely to succumb. Animals may be immunized 

 in the same manner and with the same sized doses as were directed for 

 the preparation of serum precipitins. 



Bacterial Precipitins. It is usually customary to differentiate be- 

 tween the bacterial and the protein precipitins, but for practical pur- 

 poses this division is superfluous, as the bacterial precipitins are simply 

 antiserums prepared by immunization with bacterial protein. 



PRODUCTION OF HEMOLYSINS 



Because of their use in the serum diagnosis of syphilis and other in- 

 fections, hemolysins possess great practical value. They are best pro- 

 duced by injecting rabbits with washed human or sheep erythrocytes, 

 or with those of some animal of another species. Rabbits differ con- 

 siderably in their power to form hemolysins, and for some unknown 

 reason hemolysins are more readily produced with some erythrocytes 

 than with others. It is not possible, however, to immunize every kind 

 of animal against every type of erythrocyte. As a general rule, an 

 animal produces a better hemolysin the more remote its relationship is 

 to the animal from which the erythrocytes for making the injection are 

 taken. 



Hemolysins may be prepared as the result either of intraperitoneal 

 or of intravenous injections of erythrocytes washed at least three or 

 four times to remove all traces of serum. Unless an antihuman hemoly- 

 sin is required within a short space of time, better results are obtained, 

 as a rule, by using the slower, intraperitoneal method. 



In immunizing rabbits it must be remembered that the quantity 

 of amboceptor produced bears no direct relation to the size of the doses 

 given. Thus, a highly potent hemolytic serum may be prepared by 

 three intravenous injections of from 3 to 5 c.c. of a 10 per cent, suspen- 

 sion of washed sheep cells. 



It must be emphasized that as far as possible an aseptic technic 

 should be employed, and that corpuscles used for making intravenous 



