124 THE PRINCIPLES OF IMMUNOLOGY 



certain receptors of sheep cells and goat cells. Therefore, the injec- 

 tion of ox cells leads to the production of an amboceptor containing 

 partial amboceptors specific for ox blood and partial amboceptors 

 specific for the common receptors of ox, sheep and goat cells. The 

 removal of the partial amboceptors common to all three cell receptors 

 will not remove that specific for ox cells, but ox cells will remove both 

 the specific and common fractions. This explanation has been the 

 subject of much experiment, particularly with anti-hemolysins, and 

 modern views are not entirely in accord with the original views of 

 Ehrlich. The subject will be referred to again in connection with a 

 discussion of anti-amboceptors and anti-complements. In the same 

 place will be found a discussion of the interpretation of the ambo- 

 ceptor as made up of a cytophilic and complementophilic group. 



Nature of the Antigen. In ordinary practice the entire erythrocyte 

 is employed for immunization, but attempts have been made to deter- 

 mine what fraction of the cell is truly antigenic. Ford and Halsey 

 have shown that the use of either stroma or the laked hemoglobin may 

 serve to produce hemolysins, but they obtained only questionable results 

 following the use of pure hemoglobin. Stewart obtained essentially 

 the same results. Nucleo-proteins obtained from dog blood are capable 

 of producing specific hemolysins. Pearce and his co-workers have 

 shown that nucleo-proteins from washed organs also lead to the forma- 

 tion of hemolysins specific for the homologous species. Organ and 

 cell extracts free from blood also serve as hemolysinogens ; the best 

 example is an extract of spermatozoa, for in this instance there is 

 no question of blood contamination of the extract. Of further interest 

 is the fact that ether extracts of erythrocytes, alcohol-ether extracts, 

 and extracts in 1.5 per cent, sodium bicarbonate induce the formation 

 of weak hemolysins without the coincident formation of hemagglu- 

 tinins. This indicates that the hemagglutinin and hemolytic ambo- 

 ceptor are probably separate and distinct antibodies. 



Nature of the Amboceptor. The amboceptor, although it resists 

 heat of 56 for one hour or more, is injured by heat of 60 C. for twenty 

 minutes, is almost completely destroyed by 70 C. for one hour and is 

 completely destroyed by boiling. Like antitoxin, it does not dialyze, 

 is electro-positive and is resistant to ultra-violet rays. It is carried 

 down in the euglobulin fraction of the serum protein, but by various 

 methods of purification may be obtained in an almost protein-free 

 state. The method of purification described by Kosakai is of im- 

 portance from various points of view and deserves some description 

 at this point. He requires a hemolytic serum which titrates 1-10,000. 

 This is diluted to 100 times its volume with salt solution and 5 c.c. of 

 the diluted serum are poured into 4 c.c. blood-cell suspension. The 

 union of amboceptor and red cells is accomplished by exposure at room 

 temperature for fifteen to twenty minutes, after which the cells are 

 freed from serum by repeated washing. To the antigen-amboceptor 

 combination is added isotonic or slightly hypertonic aqueous solution 

 of a sugar such as saccharose, glucose or lactose, and the mixture incu- 



