432 THE TECHNIC OF COMPLEMENT-FIXATION REACTIONS 



I. The Fluid to be Tested. (a) Serum. As a general rule, all 

 specimens of blood submitted for complement-fixation tests should be 

 collected aseptically in sterile containers. This is especially necessary 

 when there has been delay in transmitting the fluid to the laboratory, as 

 when sent through the mails from distant points. When the reactions are 

 to be conducted on the same or on the following day, the specimen of 

 blood may be collected in chemically clean but not necessarily sterile 

 containers. Bacterial contamination renders a fluid anticomplementary 

 and unfit for complement-fixation tests. Specimens should be kept on 

 ice until used, and the serum promptly separated from the clot. 



Collecting Blood for the Wassermann Reaction. In collecting blood 

 for the Wassermann reaction the following points should be remembered : 



1. That during active antisyphilitic treatment the blood may react 

 negatively, whereas at a later period a true positive reaction is observed. 

 It is well, therefore, not to collect blood until all specific treatment has been 

 suspended for at least two weeks. 



2. That blood collected during or immediately after an alcoholic 

 debauch may yield a false negative reaction (Craig and Nichols). 



3. That blood should not be collected just after anesthesia or while 

 the patient has a high temperature. 



As a general rule, at least 1 c.c. of serum and 2 c.c. of cerebrospinal 

 fluid are required for making the syphilitic reaction. From 2 to 3 c.c. 

 of blood are needed, these amounts being easily collected from adult 

 .persons by pricking the finger deeply and filling a small test-tube or 

 vial, as shown on p. 32. This method is very convenient, especially 

 for physicians, hospitals, and dispensaries where direct access to a 

 laboratory can be had. When the treatment is to be guided by the 

 Wassermann reaction, a number of tests are required, and patients may 

 object to repeated venipuncture, whereas no objections will be raised 

 to simple puncture of the finger. 



Larger amounts of blood are collected from a vein at the elbow under 

 aseptic precautions, as described on p. 33. As a rule, it is well to collect 

 at least 5 c.c. of blood, especially if the specimen is shipped from a distant 

 point (Fig. 108). An excess of serum permits the technician to repeat a 

 test when necessary, or to apply more than one method, and thus at 

 times both the physician and the patient are saved the time and annoy- 

 ance incident to collecting another specimen (Fig. 109). 



The Keidel tube, which is sterilized and ready for use, is quite a 

 convenience (p. 36). However, a test-tube or a centrifuge tube may be 

 used, or, when a specimen is to be mailed, a 5 or 10 c. c. vial of thick glass, 



