WASSERMANtt AND OTHER COMPLEMENT FIXATION TESTS 251 



Nearly all cases of active, secondary and congenital syphilis give strong 

 positive reactions when not influenced by medication or alcoholic intoxication. 

 In latent or dormant cases of secondary and congenital syphilis, strong positive 

 reactions are common, but taken as a whole they are less pronounced than in the 

 active secondary stage; and in latent tertiary syphilis, the greatest number of 

 weak positive reactions are observed; frequently the reactions are so slight that 

 they must be considered doubtful. 



As to the significance of a clear-cut positive reaction little need be said, yaws 

 and leprosy are the only diseases other than syphilis that can cause a positive 

 reaction; having excluded these, and technical error, a positive Wassermann 

 practically always indicates syphilis. 



The amount of amboceptor present in the serum of a syphilitic patient 

 gradually increases from zero in the period of incubation, to many times the 

 amount necessary to fix all the complement in o.i cc. of guinea-pig serum (using 

 o.i cc. of the patient's serum) in the secondary stage of the disease. It tends to 

 gradually decrease in the tertiary stage and may fluctuate as the disease is 

 influenced by treatment. 



As a consequence all degrees of reaction are observed in Wassermann tests, 

 made with syphilitic sera, from no complement fixation to complete complement 

 fixation. 



With our present knowledge of the serology of syphilis there is little chance 

 of error in interpreting the significance of a Wassermann reaction when all or 

 none of the complement is fixed, but when very slight amounts of complement 

 are fixed, when hemolysis is partial, not complete; in other words, when the 

 reaction is doubtful, misinterpretations are inevitable. Fortunately, the patients 

 giving such reactions are few in comparison to the whole; but they embrace a 

 considerable number of syphilitics. Erroneous conclusions in these cases can 

 be minimized by. repeated examinations of the patient's serum at weekly or 

 fortnightly intervals and making the tests with several different antigens and 

 proportioning the reagents so as to make the test most sensitive but error can- 

 not be entirely precluded; herein lies the greatest weakness of the test. 



Some apparently normal individuals and some non-syphilitic patients, espe- 

 cially those afflicted with any of the diseases classified as "chronic granulomata" 

 have in their blood serum something which tends to deviate, vitiate or fix 

 complement. 



This non-specific deviation of complement can usually but not always be 

 measured by placing o.i cc. of the suspected serum (inactivated) in each of a 

 number of tubes, adding one unit of hemolytic amboceptor and one unit of red 

 cells to each tube, and beginning with one unit of complement in the first tube 

 add gradually increasing amounts of complement to successive tubes; shake, 

 incubate for i hour and then discover the smallest amount of complement which 

 gives complete hemolysis; the Wassermann test is then made, using this amount 

 of complement as one unit. 



Occasionally a serum that gives a doubtful reaction with a salt solution ex- 

 tract antigen will give a clear-cut negative or positive with an alcoholic or ether 



