80 LABORATORY COURSE IN SERUM STUDY 



5. Supernatant fluid B 0.5 c.c. + Colon suspension 0.5 c.c. 



6. Supernatant fluid B (1-5) 0.5 c.c. -f Colon suspension 0.5 c.c. 



7. Supernatant fluid B 0.5 c.c. + Typhoid suspension 0.5 c.c. 



8. Supernatant fluid in high- 



est dilution in which it 

 agglutinated typhoid in 

 original titration 0.5 c.c. + Typhoid suspension 0.5 c.c. 



9. Salt solution . 0.5 c.c. + Typhoid suspension 0.5 c.c. 

 10. Salt solution 0.5 c.c. + Colon suspension 0.5 c.c. 



Incubate one hour at 37 C. and record results. 



Tubes 1, 2, 5 and 6 should show no agglutination if absorption has 

 been complete. If all the agglutinin has not been absorbed, however, 

 there may be clumping in tubes 1 and 5. The bacteria in tubes 3, 4, 7 

 and 8 should be agglutinated. 



GROUP AGGLUTININS 



The serum of animals highly immunized to one species of 

 bacteria will often agglutinate closely related bacteria, though 

 this action is invariably weaker than the agglutinative power for 

 the bacteria used in immunizing the animal. 



Thus the serum of an animal which before treatment agglu- 

 tinated Bacillus coli in dilutions of 1-20 and Bacillus typhosus in 

 dilutions of 1-5, after immunization with Bacillus typhosus may 

 agglutinate Bacillus coli as highly as 1-100, and Bacillus typhosus 

 up to 1-10,000 or more. This indicates a close similarity in the 

 chemical constituents of the two antigens the Bacillus typhosus 

 antigen containing small amounts of the protein present in Bacillus 

 coli. Absorption with Bacillus typhosus will remove both the 

 Bacillus typhosus and the colon agglutinins. Absorption with 

 Bacillus coli will take out only the colon agglutinin, the serum still 

 agglutinating Bacillus typhosus 1-10,000. 



The serum here contains at least two types of agglutinins, the 

 so-called major or specific agglutinin which reacts only with the 

 homologous bacteria, and the minor or group agglutinins which 

 react both with the homologous bacteria and with the allied 

 species. If such a serum is added to a suspension of the homolo- 

 gous bacteria both major and minor agglutinins are absorbed 



