HEMOLYSINS. 259 



may be used for complementing purposes, and this 

 may be as low as, or lower than, 0.1 c.c. for a par- 

 ticular experiment. 



As pointed out in the preceding chapter, the he Ab sorp- 

 combined action of amboceptor and complement is boceptors by 



... . T Cells. 



necessary for the cytotoxic action of a serum. In 

 view of the fact that the toxic power is lost by ex- 

 posure to that temperature which destroys comple- 

 ment, it seems that the latter is the actual dis- 

 solving or toxic substance, whereas the ambocep- 

 tor must play some intermediary role. Investiga- 

 tions have shown that the two act together in a 

 very definite manner in that the absorption of the 

 amboceptors by the cells is a prerequisite for the 

 absorption and action of the complement. This 

 may be verified by simple experiments: Mix 

 erythrocytes with the homologous amboceptors, 

 and after a period of from twenty to thirty min- 

 utes centrifugate the mixture and remove all the 

 free serum from the cells by repeated washings 

 with isotonic salt solution. If the cells are again 

 suspended in salt solution and a small amount of 

 complement is added and thoroughly mixed, the 

 hemoglobin is dissolved out; a control must, of 

 course, show that the complement alone has not 

 the dissolving power. The result indicates that 

 the erythrocytes during their contact with the im- 

 mune serum had absorbed or combined chemically 

 with the amboceptors, and that the latter remained 

 attached to the cells in spite of the washings to 

 which they were submitted. 



It would seem that the union of amboceptor s< 

 with cell has the effect of rendering the latter sus- 

 ceptible to the action of complement, and for this 

 reason amboceptor-laden cells are spoken of as 



