100 LABORATORY COURSE IN SERUM STUDY 



treated. This gives a rough estimate of the concentration of the antigen. 

 If the solution seems much too concentrated, dilute it until it approaches 

 1-1000, i.e. the limit of its still presenting a lasting foam on shaking. 

 Place the antiserum in the tube first and make a ring test. To do 

 this run antigen very carefully into tube with a nipple pipette so that 

 the two fluids may not be mixed. Watch for a white ring at the line of 

 junction. Be careful to compare this with the control, since a slight 

 opalescence is often seen at the line of junction of salt solution and 

 serum not due to precipitation. 



2 



1. Unknown solution (a) 0.5 c.c. + antihuman serum 0.2 c.c. 



2. Unknown solution (a) 0.5 c.c. + normal rabbit 



serum 0.2 c.c. 



3. Unknown solution (6) 0.5 c.c. + antihuman serum 0.2 c.c. 



4. Unknown solution (6) 0.5 c.c. -f normal rabbit 



serum 0.2 c.c. 



5. Known human serum (1-1000) 0.5 c.c. -f antihuman serum 0.2 c.c. 



6. Salt solution 0.5 c.c. + antihuman serum 0.2 c.c. 

 Observe the tubes for 15 or 20 minutes at room temperature. Then 



incubate and observe. After 30 minutes shake up and observe for 

 cloudiness and flocculation. 



3 



Set up a similar series with antisheep instead of antihuman serum. 

 Let each student report whether either of the specimens he received is 

 sheep or human. 



In order that conclusions may be definitely drawn from such a test 

 it is necessary that the tubes containing the unknown solution (say it is 

 suspected of being human blood) and the known human blood, 1-1000 

 control, should show a definite reaction within not longer than 10 min- 

 utes at room temperature. Antisera too weak to show such a sharp 

 reaction with controls of the known protein are not suitable for such 

 tests. 



Each student needs: 



6 f-inch test tubes. 12 Precipitation tubes 6 mm. in diameter. 

 Capillary pipettes. 



LESSON XVI 



BORDET-GENGOU PHENOMENON COMPLEMENT 



FIXATION 



THE Bordet-Gengou phenomenon is the prototype of all com- 

 plement fixation methods. It depends on the fact that antigens 



