SIGNIFICANCE OF ALLERGY 545 



aeellular ai>ar at a considerable distance from the phagocytic cells 

 unless the tissue fluids were prevented from reaching them. This 

 was in marked contrast to the inhibition of growth of the bacteria 

 in vaccinated and tuberculous animals. Apparently the fluid from 

 the tissues of normal animals penetrating the agar encouraged 

 growth of the bacteria while the tissue fluid in vaccinated or 

 tuberculous animals penetrated the agar and inhibited growth. 

 This apparently demonstrated that humoral factors play a role in 

 defense against tubercle bacilli. 



Lurie also suggests that in vivo agglutination, as well as the 

 deposition of a fibrin barrier thrown about the agar mass as a 

 whole, tends to keep the bacteria localized in immune animals. 

 It would appear that extracellular factors may be effective in 

 limiting the spread of infection when small doses are introduced. 

 When larger doses are introduced into vaccinated or tuberculous 

 rabbits, there is a greatly intensified inflammation developed and 

 the factors tending to localize the bacteria are overcome by the 

 increased lymph flow which sweeps the leucocytes and agar par- 

 ticles containing bacteria into the regional lymph nodes more 

 rapidly than in normal animals. This phenomenon has been re- 

 ported by Freund and Angevine (1938) and others. Lurie found 

 that immunity is effective in these vaccinated animals despite the 

 lack of immediate fixation. This immunity is due not only to 

 the humoral factors but to actively phagocytic mononuclear cells. 

 The bacteria that are swept into the regional lymph nodes are fixed 

 and destroyed by the humoral and tissue mechanisms. 



lAirie found the mononuclear phagocytes much more effective 

 agents in combating infection in vaccinated animals than the neu- 

 trophiles. In fact he states that the mononuclear cells derived 

 from vaccinated or actively tuberculous guinea pigs exhibit a 

 greater in vitro phagocytic capacity for tubercle bacilli and 

 carbon particles than mononuclears from normal animals. 



Lurie also notes that bacteria are fixed locally more thoroughly 

 in vaccinated or tuberculous guinea pigs than in vaccinated or 

 tuberculous rabbits although the general immunity may not differ. 

 He correlates this difference in local fixation with the differences 

 lie observed in the degree of allergic response and also the kind 

 of fibrin networks laid down. He calls attention to the conclusion 

 of Menkin (1938) that the amount of fixation of bacteria at the 



