136 IMMUNO-CATALYSIS 



cific precipitates both as immunizing and as test antigens to deter- 

 mine quantitatively the chemical relationship, not only of antibodies to 

 the different serological types of pneumococcus, but also of antibodies 

 directed against a somatic component, the so-called C polysaccharide 

 of the pneumococcal cell. 



A specific precipitate derived from anti-pneumococcus Type II horse 

 serum was used as antigen for the injections of rabbits and the result- 

 ing sera were tested against the specific precipitates obtained with: 



(a) Pneumococcus Type I, II and Group C carbohydrate and ho- 

 mologous horse sera; 



(b) H. Influenza Type B polysaccharide and anti-influenza Type 

 B horse serum; 



(c) Diphtheria crude toxoid and horse diphtheria antitoxin; 



(d) Crystalline egg albumin and homologous horse antiserum; and 



(e) Specific precipitates from Type II anti-pneumococcal rabbit 

 serum and from Type I anti-pneumococcal pig serum. 



The results showed that "after absorption with egg albumin-anti- 

 egg albumin (horse) specific precipitate and removal in this way of 

 roughly one-half of the antibody the anti-specific precipitate rabbit 

 serum still resembled the unabsorbed serum in its quantitative re- 

 activity toward a high ratio pneumococcal specific precipitate when 

 compared at the same antibody content. 



"The co-existence of separate groupings which function as antigen 

 and antibody on the same molecule of horse globulin is indicated by 

 experiments showing pneumococcus Type II horse antibody precipi- 

 tated with an excess of anti-specific precipitate rabbit serum can still 

 combine with Type II specific carbohydrate, and that the horse anti- 

 body in a solution of the egg albumin-anti-egg albumin (horse) specific 

 precipitate in an excess of egg albumin still reacts with the anti-specific 

 rabbit serum." 



Tests were carried out to examine whether the antibody specificity 

 would affect in any way their function as test antigens. Neither by the 

 sensitive quantitative agglutinin method nor by passive anaphylaxis 

 tests in the guinea pig could any variation be demonstrated due to the 

 specific antibody groupings. These and other findings led the authors 

 to the conclusion that the antigenic reactions of this representative 

 water-insoluble group of antibodies engendered in the horse are es- 

 sentially similar. These findings confirm in a more rigorous quantita- 



