594 BIOLOGY OF PNEUMOCOCCUS 



below the type-specific titer may be employed. If the serums are to 

 be used for precipitation tests, the same routine should be followed 

 in determining the titer against homologous and heterologous 

 polysaccharide. 



It is generally conceded that antipneumococcic horse serum is 

 unsatisfactory for use in the Neufeld Quellung reaction because of 

 the non-specific effects caused by that serum (Neufeld and Etin- 

 ger-Tulczynska, 1931 ; 984 Etinger-Tulczynska, 1933; 868a Sabin, 

 1933 1206 ). The British Therapeutic Trials Committee of the Medi- 

 cal Research Council (1934) 887 concluded, however, that results 

 with either immune horse or immune rabbit serum are equally re- 

 liable provided the serum has an agglutinative titer of 1 to 160 

 to 1 to 320. At the Massachusetts Antitoxin and Vaccine Labora- 

 tory it has been observed that, even when the same vaccines are 

 used for immunization purposes, immune horse serum is likely to 

 give cross-reactions, whereas immune rabbit serum is highly type- 

 specific. 



Relatively small amounts of serum are required for the Neufeld 

 test, and, therefore, it is better to use rabbit serum because of the 

 irregular reactions exhibited by horse serum. For routine identifi- 

 cation tests, and for other methods involving macroscopic agglu- 

 tination or precipitation, diagnostic horse serum may be found 

 more economical to use than rabbit serum. 



IMMUNE RABBIT SERUM 



Various methods are employed for producing antipneumococcic 

 rabbit serum for use in the Neufeld Quellung test. For the pur- 

 pose, methods outlined by Barnes and White 86 have given satisfac- 

 tory results. Cooper and Walter (1935) 275 published the details of 

 the methods employed at the laboratories of the New York City 

 Department of Health and emphasized the necessity of using scru- 

 pulously clean syringes for antigen injections, and of selecting 

 representative strains of pneumococci for immunization. It was 



