Specific Hyperleucocytosis in Immunized Animals. 47 

 27 (844) 



A further note on specific hyperleucocytosis in immunized animals. 



By Frederick P. Gay and Edith J. Claypole. 



[From the Hearst Laboratory of Pathology and Bacteriology, Uni- 

 versity of California.] 



In a previous communication, 1 we have mentioned the specific 

 and extreme hyperleucocytosis which occurs on injecting a culture 

 of the typhoid bacillus in a typhoid immunized rabbit. Further 

 study shows that this reaction precedes and is remarkably more 

 intense than the reaction that occurs on injecting B. typhosus in 

 normal rabbits. In both instances there is an initial leucopenia 

 two hours after injection followed by a rise and subsequent fall 

 and a second higher rise in both normal and immunized rabbits. 

 A mean of a considerable number of determinations shows that in 

 immunized animals the first rise occurs at about 12 hours and 

 averages a leucocyte count of 62,800. Counts of 100,000 to 

 150,000 have occurred not infrequently. This is followed by a 

 fall at about 16 hours followed by a second rise which reaches at 

 18 hours an average of 74,700 leucocytes. In the normal animal 

 these two rises are also evident, occurring at 18 and 26 hours 

 respectively, and giving an average of 39,200 and 37,000 leucocytes 

 to the cubic millimeter. 



This specific type of leucocytosis has also been found to occur 

 in rabbits immunized against red blood cells (sheep and guinea 

 pig) and also against horse serum. In both these instances the 

 highest leucocyte count occurs much sooner than in the case of 

 typhoid immunized animals, somewhere between 4 and 8 hours 

 following injection. It does not occur with equal intensity in all 

 animals, and the intensity would seem, from preliminary observa- 

 tions, to bear some relation to the hemolytic titer or the precipitin 

 titer of the animal concerned. This latter fact led to a crucial 

 experiment designed to expose the mechanism by which the specific 

 hyperleucocytosis is produced. 



It is found that when a normal rabbit is given an intravenous 

 injection of 1 c.c. of well-sentitized sheep-blood corpuscles, subse- 



1 Journal American Medical Association, LX, 1913, 1950. 



