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Cellular Immunity : Observations on Natural and Acquired 

 Immunity to Cohra Venom. 

 By J. A. GuNN and E. St. A. Heathcote. 



(Communicated by Prof. Sherrington, F.E.S. Received October 16, 1920.) 



(From the Pharmacology Laboratory, Oxford.) 



Introductory {J. A. G^mn). 



While the properties acquired by the serum of an animal as the result of 

 immunisation to a toxin of the bacterial type have been examined with an 

 exhaustive minuteness, little of the now vast literature on immunity has 

 concerned itself with the cellular as opposed to the humoral aspect of 

 immunity. Little, and less that is certain, is known of the changes that 

 immunisation produces in living cells other than the white blood corpuscles. 

 The part played by these cells in immunity processes, so fruitfully studied 

 by Metohnikoff and others, is responsible by itself for an extensive literature 

 which cannot be dealt with here. Accurate information is still wanting in 

 regard to the part played by other living cells in the acquisition and 

 retention of immunity. One reason for this is that investigation has been 

 confined too exclusively to the blood. This has been partly and justifiably 

 due to the diagnostic, therapeutic, and other importance of immune sera; 

 also, perhaps, to the fact that the technique of blood investigation is more 

 easy and generally familiar than the technique necessary to deal with other 

 tissues. Another reason, no doubt, is that there are relatively few toxins 

 which produce true immunity that lend themselves to the kind of investiga- 

 tion adopted in the experiments to be described. 



Without attempting the task, here unnecessary, of making a complete 

 survey of the literature on cellular immunity, I wish to state briefly the 

 present state of knowledge in regard to certain factors which have been 

 investigated as explanatory of (a) natural, and {b) acquired immunity. 



(a) Natural Immunity. — It is now generally believed that natural 

 immunity either to drugs, poisons, or toxins is seldom, if ever, due to 

 the presence of antitoxin in the blood of the immune animal. For example, 

 Calmette and Delearde(l) found that there is no antitoxic substance in the 

 blood of reptiles capable of explaining the relative natural immunity which 

 they possess to venom ; and similarly, that the sera of the fowl and 

 tortoise, which resist high doses of abrin, are completely devoid of antitoxic 

 power. Though they did find that the sera of the mongoose and hedgehog 



