22,4 Goodpasture: Complement Fixation in Leprosy 431 



best results, yielding a positive test in 100 per cent, although five 

 cases required 0.2 cubic centimeter of serum for fixation. One 

 serum fixed complement with this antigen in 0.0005 cubic cen- 

 timeter quantity. Bacillus tuberculosis of bovine and avian 

 types and B. smegmatis were also excellent antigens, and several 

 acid-fast organisms isolated from leprous lesions served almost 

 equally well. 



Before selecting B. tuberculosis (human) as an antigen for 

 the following tests, antigens composed of four other organisms 

 were compared with it. These organisms were two very distinct 

 strains of streptothrices, B. smegmatis, and the mist bacillus. 

 Antigens were prepared uniformly as follows: 



The organisms were grown on glycerinated broth (in the case 

 of Bacillus tuberculosis on glycerinated agar also) , the culture 

 suspended in broth, and precipitated by the addition of an equal 

 volume of 95 per cent alcohol. The precipitate was removed 

 by filtration or by centrifuging, and dried over sulphuric acid. 

 It was weighed and ground in a mortar with sufficient sodium 

 chloride so that, by the addition of distilled water, a 2 per cent 

 isotonic suspension could be made. The 2 per cent suspension 

 was shaken thoroughly with glass beads and used as stock an- 

 tigen. In performing the test a 1 to 10 dilution was used. 

 One cubic centimeter of this dilute antigen was not anticom- 

 plementary, and 0.5 cubic centimeter was used as the antigenic 

 dose in each test. 



Table 5 illustrates the relative value of these antigens with 

 sera from five cases of nodular leprosy. Streptothrix II is a 

 non-acid-fast organism, and Streptothrix I is acid-fast only in 

 certain forms. 

 Table I 





The observation was made by Cooke that the value of a 

 particular acid-fast organism as an antigen depends very largely 

 on the physical character of its suspension in salt solution. The 

 finer and more nearly even suspensions yielded the better results. 



