860 IMMUNOLOGY 



mains constant in experimental rat 977 because the trypanosomes are not 

 reproducing. As was indicated above, ablastin is not absorbed by the 

 trypanosomes in vitro, whereas the trypanocidal antibodies are. There is 

 thus no lasting union of trypanosomes and ablastin, nor is there a sensiti- 

 zation of trypanosomes by ablastin as there is with the trypanolysins. 

 Moreover, if smaller and smaller doses of trypanocidal antibody are 

 given, a point is reached at which the trypanosomes are not killed, but 

 their reproduction remains unaltered. A group reaction can be demon- 

 strated between T. duttoni and T, leivisi and their ablastins in vivo, and 

 between T. lewisi and 2iX\tiduttoni trypanocidal antibody in vivo and iti 

 vitro; but whether the reaction of anti/^'w/w trypanocidal antibody against 

 T. duttoni in vivo and in vitro is a true group reaction of an immune anti- 

 letvisr antibody is not evident because normal rat serum is also trypano- 

 cidal to T. duttoni. These statements are based on a series of investiga- 

 tions involving either or both of the following: in vitro work for the 

 trypanocidal effects and in vivo passive transfer experiments for all three 

 effects by W. H. Taliaferro and coworkers [vide infra), Regendanz and 

 Kikuth (1927), Perla and Marmorston-Gottesman (1930) and co- 

 workers, W, H. Taliaferro, Cannon, and Goodloe (1931), and W. H. 

 Taliaferro (1932). Culbertson (1938) has shown that the immunity to 

 T. lewisi is passed through the mother's placenta and milk to young rats 

 where it persists for several weeks. Later, Culbertson and Wotton 

 (1939) found that the young rats do not appear to produce ablastin as 

 promptly or as well as older rats. 



Various procedures designed to lower the macrophage function, such 

 as splenectomy, especially if combined with India-ink blockade or some 

 infection such as Bartonella which affects the macrophage system, de- 

 crease the strength and delay the appearance of ablastin and the terminal 

 trypanolytic antibody (Regendanz and Kikuth, 1927; Perla and Mar- 

 morston-Gottesman, 1930; Regendanz, 1932; and W. H. Taliaferro, 

 Cannon, and Goodloe, 1931). This is an effect on acquired immunity. 



The next question which arises is whether the macrophages or other 

 phagocytic cells assist in passive immunity or in the action of ablastin 

 or the trypanolysins in the body. The work of W. H. Taliaferro (1938) 

 indicates the following: Splenectomy and blockade have no effect on the 

 passive transfer of ablastin, but the following interesting secondary 

 effect results: The passive transfer of ablastin lasts only for a few days. 



