PRODUCTION OF ANTIPNEUMOCOCCIC SERUM 527 



made during the routine work in manufacturing laboratories. At 

 present, therefore, the most satisfactory antigen for stimulating 

 the production of type-specific therapeutic serum is one composed 

 of a natural combination of the pneumococcal protein and poly- 

 saccharide as found in the intact cell, and containing a minimum 

 of uncombined carbohydrate and somatic protein. 



Exudates of infected tissues. Exudates of infected pneumonic 

 tissue have also been tried as immunizing agents. Netter (1887) 969 

 obtained immunity in mice and rabbits by the injection of post- 

 pneumonic pleural exudate, and the Klemperer brothers (1891) 724 

 observed similar results. Hartman (1913) 599 also described the use 

 of the various constituents of exudative material as antigens but 

 the results were disappointing. A vaccine prepared from pneumo- 

 cocci washed from the peritoneal cavity of a rabbit dead from 

 pneumococcal infection was, according to Heist and Solis-Cohen 

 (1919), 635 more active as an immunizing agent for rabbits than 

 one made from the organisms grown on artificial culture media. 

 Freedlander (1928), 480 by using saline extracts of infected tissues 

 as antigens in rabbits, claimed to have obtained protective serum 

 of a potency corresponding to that of antipneumococcic horse se- 

 rum. In 1929, Curphey and Baruch 291 described a method of col- 

 lecting and using pleural exudate from horses in the immunization 

 of other horses against pneumococci. The authors believed that the 

 procedure would decrease the length of time necessary to produce 

 a potent immune serum. A year later, these investigators 292 re- 

 ported the results of tests with the so-called exudate antiserum. 

 The effects of the serum in treating intradermal infections in rab- 

 bits were compared with those of serum prepared in the usual 

 manner, and in the opinion of the authors the exudate antiserum 

 contained antibodies other than those of an antibacterial nature. 



Viability of the organism. The question whether dead pneumo- 

 cocci are more or less efficient antigens than living pneumococci is 

 still unsettled. Mosny (1892), 932 already quoted, stated that when 

 cultures are to be used for immunization, "they must be virulent 



