170 THE PRINCIPLES OF IMMUNOLOGY 



influence, they do not materially favor phagocytosis but appear to 

 augment the migration of leucocytes to a slight degree and possibly are 

 of importance in this way because of the fact that they exert positive 

 chemotaxis. Zinsser states " we are inclined to believe at present that 

 the beneficial effects of leucocyte extracts are based on the same prin- 

 ciples as those which determine the reactions following on the injection 

 of bacterial and any other protein." To us it appears that this method 

 is to be included in the category of non-specific therapy previously 

 discussed (page 30). 



Specific Hyperleucocytosis. Following upon the earlier sug- 

 gestion of Bordet, Gay and his collaborators found that immune animals 

 exhibit a much higher degree of leucocytosis following the injection 

 of the organism to which they had been immunized than do normal 

 animals. For example, rabbits immunized to typhoid bacilli reacted 

 to subsequent injections of typhoid bacilli. with blood counts of as high as 

 150,000 leucocytes per cmm., whereas normal rabbits showed a reaction 

 of only 40,000 to 50,000 leucocytes per cmm. This phenomenon of spe- 

 cific hyperleucocytosis has been contradicted by McWilliams, who found 

 no important difference in response between normal and immune animals 

 and further states that typhoid immune rabbits react in essentially the 

 same degree to colon bacilli as to typhoid bacilli. Others have confirmed 

 the work of McWilliams. Zinsser and Tsen found a slight favorable 

 difference in animals immunized to Gram negative cocci and a somewhat 

 more marked difference in those immunized to Gram positive cocci, not 

 in any case, however, to the degree indicated by Gay. There seems 

 little reason for believing that a specific hyperleucocytosis plays any 

 important part in resistance to infection. This, however, is not to be 

 construed as an argument against vaccination, since the latter procedure 

 is important in the production of specific opsonins, agglutinins and other 

 immune bodies. Any response to vaccination in the form of leucocytosis 

 must be regarded as only in small part if at all specific and is probably 

 of the same nature as the leucocytic response to the injection of non- 

 specific proteins and their products. 



The Lymphocytes. Lymphocytes appear in inflammatory areas as 

 the result of infection, but accumulate in largest amounts in chronic 

 inflammatory areas where, in most instances, the active infective agent 

 is no longer present. The part they play in the phenomenon of inflam- 

 mation and in protection against infection is not understood. From 

 the work of Opie it seems probable that the lymphocytes may be, in 

 part, the source of the ferment which he describes as operating in 

 weakly acid media. As pointed out above, this ferment was obtained 

 from hyperplastic lymph-nodes. The lymphocytes are said to contain 

 a lipase, and it is suggested that the large collections of these cells 

 about tuberculous foci may serve by the action of the lipase to break 

 down the waxy shell of the bacilli. The lymphocyte is stated to possess 

 phagocytic properties, but these are at best very slight and probably 

 play no important part in resistance to disease. It has long been noted 

 that the presence of tumors in the body often excites a neighboring 



