414 BIOLOGY OF PNEUMOCOCCUS 



berger and Kendall, 625 who, by the use of strong salt concentration 

 and proper adjustment of the hydrogen ion concentration well on 

 the alkaline side, obtained from pneumococcal polysaccharide- 

 homologous antiserum precipitates a protein substance of which 

 93 per cent of the total nitrogen was in the form of immune body 

 nitrogen. 



Heidelberger and Kendall took the precaution of removing from 

 their source material — unconcentrated Type I, II, and III anti- 

 pneumococcic serum — somatic protein antibodies and somatic car- 

 bohydrate (Fraction C) antibodies, thus reducing the antibody 

 content of the serum to antipolysaccharide antibodies. By employ- 

 ing unconcentrated serum without chemical treatment, any pos- 

 sible denaturation of the antibody was avoided and the antibody 

 dissociated from the specific precipitate was considered as being 

 presumably free from artificial concomitants. 



By dissociating antibody from similar antigen-antibody precipi- 

 tates and then by purifying the antibody by dialysis with subse- 

 quent precipitation at its isoelectric point, Chow and Wu 227 suc- 

 ceeded in obtaining a protein preparation of high precipitating 

 activity, which they considered as representing an immunologically 

 pure protein. 



The work of Wyckoff 1555 and of Heidelberger, Pedersen, and 

 Tiselius 629 further attests the protein nature of pneumococcal an- 

 tibody and points to a distinction between specific immune globu- 

 lin and the globulin of normal horse serum. However, there still 

 remain discrepancies to be explained. None of the antibody prepa- 

 rations so far obtained can be regarded as pure in the strict sense 

 of the word from either a chemical or an immunological viewpoint. 

 As Chow and Goebel remarked, no end-product ever attains a value 

 of 100 per cent of type-specific precipitable protein. Yet the evi- 

 dence that has accumulated in the past few years makes it difficult 

 to escape the conviction that pneumococcal antibody is a protein, 

 undoubtedly of the pseudoglobulin type, and that it is a chemical 

 entity distinct from native serum pseudoglobulin. 



