156 THEORIES CONCERNING IMMUNITY 



IMMEDIATE AND SECONDARY RESULTS OF THE 

 CONDITION OF IMMUNITY- AN APHYL AXIS. 



An organism which has been immunized or sensitized by an 

 antigen is no longer a normal organism, and it will remain 

 abnormal as long as it will produce antibodies in excess. 



The principal object of research concerning active immun- 

 ity up to the present, was to obtain an immediate result: in 

 immunity an accrued resistance against spontaneous or 

 experimental infection; in anaphylaxis, a more or less severe 

 rapid crisis or vaccination against this crisis. 



It was known that although in certain cases (tuberculosis, 

 syphilis) immunity and anaphylaxis ceased to exist during 

 the period of infection in the large majority of cases, immun- 

 ity and anaphylaxis are more or less lasting chronic states; 

 and we have seen above (Arthus' phenomenon) that experi- 

 mental intensive immunization of animals ends most often 

 in chronic morbid states. 



When horse serum in very small doses (0.01 c.c. to 0.1 

 c.c.) is injected into the vein of a rabbit, and when this 

 injection is repeated daily, or even two or three times daily 

 for several weeks, no crisis of acute anaphylaxis is ever 

 observed, although the rabbit serum after the first fortnight 

 becomes a strong precipitant of horse serum. The immunity 

 of the rabbit against these injections is explained by the 

 action of the small doses which are vaccinating one for the 

 other. 



If, after this series of injections which occasioned no note- 

 worthy incident, the rabbits are kept at rest and under 

 observation, it is found two or three months later that, out 

 of a dozen animals so treated, one or two will show nerve 

 palsies, others dermatoses with alopecia, others rheumatism ; 

 and even if no accidental infectious disease interferes with 

 the experiment, at the end of a year only one or two animals 

 will remain alive. All the others will have been affected by 

 more or less well characterized chronic diseases, and will have 

 succumbed to cachexia. 



Similar phenomena are observed with all horses that have 

 been intensively immunized for the production of antitoxic 

 or antibacterial sera. 



