PRODUCTION OF ANTIPNEUMOCOCCIC SERUM 555 



calcium phosphate dissociation of an SSS-antibody complex was 

 pH 6.7 and above, corresponding roughly to the fraction of im- 

 mune serum obtained by 36 to 50 per cent saturation with am- 

 monium sulfate. The various modifications of the methods of Gay 

 and Chickering and of Huntoon are of academic interest and af- 

 ford means of studying and analyzing the immune substances, but 

 it seems unlikely that the procedures have sufficient practical ap- 

 plication to warrant consideration for large-scale concentration 

 of serums. The probable presence of residual antigenic substance 

 in preparations made by either the original or modified methods is 

 one of the more important objections to the antibody solution ob- 

 tained in this manner. 



The use of metallic salts in preparing antibody solutions was 

 introduced by Felton 410 during studies designed to increase the 

 yield of immune substances obtained by alcohol precipitation. 

 Treatment of the total water-insoluble protein of antipneumococ- 

 cic serum with either aluminum chloride at pH 5.2 or with zinc 

 chloride at pH 7.0 caused heavy precipitation, with the immuno- 

 logically active protein remaining in solution as the metallic salt. 

 When freed from zinc by means of a carbonate or phosphate, the 

 water-insoluble protein was highly protective for mice. As far as 

 can be learned, antibody solutions prepared by this or similar 

 methods have not progressed beyond the experimental stage. 



The use of ultrafiltration as a means of purifying antibody is a 

 more recent development. Goodner, Horsfall, and Bauer (1936) 539 

 applied the method to rabbit serum, horse serum, and concentrated 

 horse serum containing antibody for Type I pneumococci. With 

 membranes having a pore diameter of 102.5 millimicrons, the fil- 

 trates of the horse and rabbit serums contained 76.7 and 86.6 per 

 cent respectively of the total antibody, while at a pore diameter of 

 188 millimicrons the filtrate of concentrated horse serum con- 

 tained 100 per cent of the antibody. It is possible that ultrafiltra- 

 tion may prove to be of practical value in the routine production 

 of concentrated antipneumococcic serum. 



