338 IMMUNOLOGICAL METHODS OF DIAGNOSIS 



THE LUETIN REACTION. 



While a number of different investigators had previously attempted 

 a skin reaction diagnosis in connection with syphilis, satisfactory 

 results could hardly be expected so long as the successful cultiva- 

 tion of the corresponding spirochete in pure culture had not been 

 accomplished. The solution of the latter problem we owe to the 

 painstaking work of Noguchi, and to the same investigator belongs 

 the credit of having first prepared an antigen with which a specific 

 syphilitic reaction may be obtained in a large percentage of infected 

 individuals. 



Preparation of the Antigen. Pure placental ascites agar cultures 

 of the pallida are ground up in a mortar with placental ascites 

 bouillon cultures of the organisms until a fairly thin emulsion is 

 obtained. This is sterilized for one hour at 60 C. and treated 

 with tricresol to the extent of 0.5 per cent. The resultant product 

 Noguchi has termed luetin. After being tested for its sterility it 

 is ready for use. A similar preparation is made from sterile culture 

 material and constitutes the control fluid. 



Injection of the Patient. Before using, the contents of the luetin 

 bottle, which must be kept in the ice-box and frequently examined 

 for its sterility, should be thoroughly shaken, so as to bring about 

 an even suspension of the spirochetes. With a sterile pipette equal 

 parts of the luetin and sterile saline are then placed in a tuberculin 

 syringe and 0.07 c.c. injected in the case of an adult and 0.05 c.c. 

 in infants. The injections are made intracutaneously, the left arm 

 being chosen for the luetin and the right arm for the control fluid, 

 of which a corresponding amount, likewise diluted with saline, is 

 used. Separate syringes are kept for the luetin and the control 

 fluid. Noguchi, moreover, advises that each arm be injected at 

 two points, about 5 cm. apart. Considering the severity of some of 

 the reactions, however, I should personally advise single injections. 



Reactions. While in non-syphilitic individuals the effect of the 

 luetin and the control injection is identical and merely represents 

 a slight traumatic reaction, which recedes within forty-eight hours 

 and leaves no induration, there may be a marked difference between 

 the two sides in syphilitic persons. Noguchi here distinguishes three 

 types of reaction at the points where the luetin has been injected. 



