COMPLEMENT FIXATION TEST IN TYPHOID FEVER 1 93 



strains) is absolutely essential. The serum from a typhoid fever patient 

 gave a strong complement fixation test with an antigen made up from his 

 own typhoid bacteria isolated from the blood but did not react with a 

 similar antigen made from seven other different strains. The antigen is 

 prepared like the artificial aggressins of Citron, by growing the bacteria on 

 agar for 24 hours. The growth is washed off in a very small quantity 

 of sterile distilled water; kept at 6o-jo C. for 24 hours (Leuchs); after 

 this the emulsion is shaken thoroughly with glass beads for 24 hours and 

 then centrifugalized until the supernatant fluid is absolutely clear. 



The antigen is titrated as usual (see Wassermann reaction, gonococ- 

 cus fixation test). The antisheep system is used. 



On testing the bloods of thirty-six patients in different stages of the 

 infection with such an antigen prepared from twenty-eight different 

 strains, the editor found a positive result in all but one instance. [This 

 patient died before the test could be repeated.] In ten cases two or three 

 examinations were necessary before the reaction became positive. For the 

 sake of comparison, agglutination tests and blood cultures were made at 

 the same time. No distinct relationship between the three could be dis- 

 covered. In several instances the complement fixation test appeared 

 earlier than the Widal or even before the blood culture became positive. 

 (In one, confirmed by autopsy, as early as the end of the first week.) As 

 a general rule, however, the complement fixatives appear later during the 

 disease, at a time when the bacteria have disappeared from the circulation. 

 Thus, this method becomes of importance as corroborative of the Widal 

 test. The positive reaction becomes stronger during convalescence and 

 persists for several months after. 



The exact clinical value of the reaction and its specificity require 

 further statistics. One can assume, however, that almost all typhoid 

 fever patients develop complement fixatives sooner or later, and that 

 these can be detected if repeated examinations with a sufficiently poly- 

 valent antigen are undertaken. 



VI. The Differentiation of Proteids by the Method of Neisser and Sachs. 



The technique employed here varies only in a few details from the 

 method advanced later by Wassermann and Bruck for the diagnosis of 

 bacterial infections. 



Neisser and Sachs do not employ a constant amount of complement (o.i), but first 

 titrate the complement against the hemolysin in double its minimum hemolytic dose. 

 For the test one and a half to two times the smallest amount of complement is necessary. 

 The hemolysin consists of the serum of a rabbit immunized against ox's blood. This 

 hemolysin acts both for ox's and sheep's erythrocytes. 



The amount of antiserum (for example antihuman serum) used for the 

 test, is influenced by two factors. 



13 



