856 EXPERIMENTAL INFECTION AND IMMUNITY 



EXERCISE 34. ANTIGENS FOR THE WASSERMANN REACTIONS 

 EXPERIMENT 85. PREPARATION OF ANTIGENS FOR THE WASSERMANN 

 REACTION 



1. Prepare 50 c.c. of an alcoholic extract of syphilitic liver (see page 420). 



2. Prepare an extract of acetone-insoluble lipoids from 20 grams of beef heart 

 (see page 422). 



3. Prepare 50 c.c. of a cholesterinized alcoholic extract of human heart (see 

 page 421). 



(a) Are antigens for the Wassermann syphilis reaction specific? 



(b) Upon what does the high specificity of the Wassermann reac- 

 tion depend? 



(c) What constitutes a specific antigen for the Wassermann reac- 

 tion? 



(d) Discuss the important relation of antigen to the Wassermann re- 

 action. 



EXERCISE 35. ANTIGENS (Continued) 

 EXPERIMENT 86. METHODS OF TITRATION OF ANTIGENS 



While the above extracts are in the course of preparation, stock ex- 

 tracts may be used for titration. After the student has finished the 

 above three extracts, they are titrated in a similar manner. 



1. Dilute 1 c.c. of an alcoholic extract of syphilitic liver in a test-tube 1:10 by 

 slowly adding 9 c.c. of normal saline solution. Dilute a cholesterinized extract (1 : 20) 

 by slowly adding 9.5 c.c. salt solution to 0.5 c.c. of extract. 



2. Conduct the anticomplementary titration of each (page 428). 



3. Conduct the antigenic titration of each (page 431). 



(a) What is meant by the anticomplementary dose of an antigen? 



(b) What is meant by the antigenic dose of antigen? 



(c) Why are these titrations so important? 



(d) In a complement-fixation test what would be the result if the 

 antigen were used in the anticomplementary dose? What would be 

 the result if the antigen were used in less than the antigenic dose? 



(e) What constitutes a satisfactory antigen for any complement-fix- 

 ation test? 



(f) In conducting a diagnostic reaction, should the antigen be used 

 in exactly one antigenic dose or double or treble this amount? Why 

 and under what conditions would this be a safe procedure? 



(g) Why should the antigen be diluted slowly with salt solution? 

 (h) Why is a serum control so important in these titrations? What 



other controls are used and why? 



