22,4 Goodpasture: Complement Fixation in Leprosy 435 



of the response of the patient. In case the reaction remains 

 strongly positive and shows no tendency to weaken even after 

 clinical "cure" of leprous foci, a complicating tuberculous infec- 

 tion should be suspected. 



The antigen used in the above tests allows complete haemolysis 

 with syphilitic sera strongly positive with lipoidal antigen; 

 consequently, a positive reaction offers no confusion with a coin- 

 cident syphilitic infection. With many normal sera, and sera 

 from various other diseases, the reaction has been uniformly 

 negative. No test was made with tuberculous serum, though 

 presumably the reaction would be positive. 



DISCUSSION 



A reliable serological method of measuring the response of 

 leprous patients to treatment with chaulmoogra oil and its 

 products would add invaluable data to the present evidences of 

 clinical improvement and of the disappearance of acid-fast 

 organisms from superficial lesions. An ideal method would be a 

 specific complement-fixation test that would be positive in 100 

 per cent of untreated cases and that would become negative only 

 after complete cure. It is futile at the present time to hope to 

 obtain an antigen specific for leprosy ; but the need is important 

 enough to stimulate thorough investigation of antigens which 

 may prove of practical value. The observations recorded above 

 show that the Wassermann reaction is hardly worthy of further 

 investigation as a possible test of broad application in leprosy, 

 although of considerable immunological interest. Bacillus tu- 

 berculosis of the human type has given promise of being an 

 antigen that may be of service, and thorough investigation of 

 it is strongly recommended. 



The sera of bacteriologically positive cases of leprosy contain 

 complement-binding substances which react with suspensions of 

 various acid-fast organisms, and especially well with B. tuber- 

 culosis, having yielded 100 per cent positive fixations in a series 

 of twenty-four cases. The physical character of the bacillary 

 suspension is of importance in selecting a suitable strain of 

 B. tuberculosis; those forming the finest and most homogeneous 

 suspensions will undoubtedly prove to be the best antigens, and 

 it would be inadvisable to begin a series of studies unless a suit- 

 able strain fulfilling this requirement be used. 



An extensive study of the subject has not been permitted, but 

 there are certain very definite lines of investigation which are 

 suggested by the results already obtained. It would seem 

 important to titrate the sera of leprous cases before treatment 

 is instituted to determine whether or not a relation exists between 



