BACTERIAL ANTIGENS AND ENDOTOXINS 



tion such endotoxins will (a) provoke a pyrogenic response 

 by liberating from polymorphonuclear leucocytes and 

 possibly other types of mesenchymal cells a cell-product 

 acting directly on the temperature-controlling centres of the 

 hypothalamus, {b) provoke a rapid but transient develop- 

 ment of power to eliminate the pyrogen much more rapidly, 

 {c) by intravenous injection precondition a rabbit so as to 

 allow acute production of antibody in tissue culture of its 

 spleen cells (Stevens and McKenna, 1957), {d) adsorb pro- 

 perdin and initiate a subsequent acute rise in the properdin 

 content of the serum, (e) condition cells (? endothelial) 

 to respond to a subsequent stimulus of the same type by 

 a destructive lesion giving the haemorrhagic patches of the 

 Shwartzman phenomenon. 



In general we can say that an appropriate endotoxin 

 preparation has very much the same effect in a normal rabbit 

 that antigen has in an immunologically conditioned animal. 

 Stevens and McKenna specifically make this comparison in 

 regard to the capacity to produce antibody against bovine 

 gamma globulin in vitro; the Shwartzman reaction is much 

 like a hyper-acute Arthus reaction, properdin more and 

 more takes on the appearance of a stop-gap non-specific 

 antibody. 



There is still an absence of much of the data necessary to 

 substantiate the point of view, but these properties of bacterial 

 endotoxin obviously call for very much the same sort of 

 formulation as we developed for the varying reactivity of 

 mesenchymal cells to antigenic determinants. Suppose we 

 adopt the convention that X is the corresponding antigenic 

 determinant for an immunologically differentiated cell or 

 endotoxin in relation to any mesenchymal cell. Then we 

 can postulate that first minimal effective contact with 

 X activates the cell in the following ways : 



(i) It becomes progressively more liable to destruction by 

 renewed contact, within 24 to 48 hours, with X. 



(ii) It liberates properdin over the same period. 



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