212 



A MANUAL OF BACTERIOLOGY 



Deflection, deviation, 1 diversion or blocking of complement. 

 Pfeiffer in 1895 observed that a large amount of immune serum 

 might not protect an animal from the cholera vibrio, while a 

 smaller amount with the same dose of vibrio did so. In 1901 

 Neisser and Wechsberg demonstrated an analogous reaction 

 in vitro. They studied the effect of a bacteriolytic immune serum 

 when varying amounts of the inactivated serum were employed. 

 The quantity ranged from 0-0005 c.c. to 1 c.c. To each of these 

 amounts constant volumes of normal serum and bacterial suspen- 

 sion were added. No bacteriolysis occurred when large and small 



amounts of immune serum were 

 used, but with medium amounts 

 bacteriolysis was complete. They 

 explained this anomalous reaction, 

 the absence of bacteriolysis with 

 large amounts of immune serum, 

 as follows : When the amboceptors 

 are in large excess, a portion 

 combines with the complement, 

 leaving some amboceptors free, 

 and these free amboceptors then 

 unite with the receptors before 

 the activated amboceptors (ambo- 

 ceptors + complement) do, and 

 thus the complement-amboceptor 

 groups are rendered inert. The 

 reaction is represented diagram - 

 matically in Fig. 34. Arrhenius, 

 however, does not accept this 

 explanation. He says : " If we have the compounds ea and db which 

 may combine to form the compound eab, the formation of the latter 

 depends wholly upon whether e has a greater affinity for ab than 

 for a. If not, then eab is not formed, even if a is not present in 

 excess." (a = amboceptor, e = microbe, b = complement.) The 

 phenomenon may be analogous with the inhibition met with in 

 agglutination (p. 225). Thj0tta, 2 from a number of carefully - 



1 " Fixation of complement " (p. 218) is frequently erroneously termed 

 " deviation of complement." 



2 Journ. of Immunology, v, 1920, No. 1. 



FIG. 34. Diagram to represent 

 the condition of the blood in 

 which there is an excess of 

 amboceptors (Neisser - Wechs- 

 berg phenomenon). The ambo- 

 ceptors (white) unite with both 

 complement (black) and re- 

 ceptors (dotted), so that the 

 receptors cannot combine with 

 the amboceptor - complement 

 groups. 



