132 



LABORATORY COURSE IN SERUM STUDY 



GONOCOCCUS COMPLEMENT FIXATION 



The antigen provided is a distilled-water extract. It is to be diluted 

 1-10 with 0.9 per cent saline solution. The preliminary titration is 

 done exactly as with the typhoid emulsion in the preceding lesson in 

 order to determine the " anticomplementary dose" of the antigen. 

 That amount which just shows beginning inhibition of haemolysis when 

 two units of amboceptor and two units of complement (0.5 c.c. of 1-10 

 dilution) are used is designated the anticomplementary dose, and one 

 quarter of this dose is used as the dose of antigen in the test. Supposing 

 that this anticomplementary dose is found (with 0.5 c.c. of 1-10 guinea 

 pig serum, 0. 5 c.c. of 5 per cent sheep cells, and two units of amboceptor) 

 to be 2.0 c.c., then the tests are set up as follows : 



Bring up to 2.0 c.c. with salt solution. 



Incubate one hour in the thermostat at 37 C. or if possible four 

 hours in the ice box at 10 C. Then add 0.5 c.c. sheep cells sensitized 

 with two units of amboceptor and incubate at 37 C. until all the tubes 

 excepting Tube 1 are completely laked. The positive serum is either 

 the serum of a rabbit which has been immunized with gonococci or the 

 serum of a patient known by previous tests to have a positive gonococcus 

 fixation reaction. All the sera are of course inactivated at 56 C. for a 

 half hour before use. 



it is boiled in distilled water and thoroughly scrubbed. It may be dried in 

 the air for 48 hours and put away or attached to a filter flask and sterilized to 

 be ready for use. Do not use for filtering gonococcus antigen a filter that has 

 been used for any other purpose, unless it is first boiled in 1 per cent NaOH and 

 reneutralized. 



Bottle the filtrate with aseptic precautions. Sterilize three successive days 

 for one half hour each day at 56 C. and keep in the ice box. Immediately before 

 use the antigen is made isotnic by the addition of one part 9 per cent saline solu- 

 tion to nine parts antigen. The antigen is more likely to remain stable if no salt 

 is added until the day of use. 



