The "Lateral-chain Theory" of Immunity 119 



If now these should also be appropriated, a further regeneration 

 occurs, and so on and on until, the cell continuing to live and more 

 and more receptors thus being formed, their number eventually 

 becomes so excessive that the cell is encumbered with them and 

 throws them off into the surrounding juices where they continue 

 to circulate as "free receptors" or "haptines" for a cpnsiderable 

 time, retaining the same combining power for circulating hap tophores, 

 that they possessed on the cells. 



In this statement may be found an explanation of several facts 

 in regard to immunity: 



1. The injury effected by micro-organismal products is in part due 

 to the adaptations between their haptophores and the receptors by 

 which the cells are starved or poisoned. This only applies to those 

 products that correspond to what are known as antigens, and not 

 to acids, alkahes, etc. 



2. The increase in the resisting power of the animal during disease 

 or after repeated experimental administration of sub-lethal doses 

 of a toxin, is due to the regeneration of receptors. 



3. The appearance of substance (antibody-antitoxin) in the blood 

 of the animal, is due to the presence in the blood of the haptines or 

 free receptors, cast off by the cells after excessive regeneration. 



This is the general statement and is the foundation of the theory, 

 but to fulfil all of the requirements of the comphcated facts of im- 

 munity, it is necessary to ampUfy the matter by modifying the nature 

 of the receptors. Ehrlich therefore supposes the existence of re- 

 ceptors of three orders: 



I. Receptors of the First Order (Antitoxins and Anti-enzymes). — 

 These have just been discussed in making plain the general prin- 

 ciples of the theory. Every cell is conceived to have innumerable 

 receptors of many orders, with many different adaptations, so the 

 student must not conceive that the condition is simple. Receptors 

 of the first order are regarded as adapted to food molecules. The 

 haptophores fit on directly, and may be simple or complex. In the 

 case of the micro-organismal enzymes and toxins, Ehrlich describes 

 such of the molecular groups as composed of a haptophore and a 

 toxophore. By the attachment of the haptophore, the toxin may be 

 brought into the cell and its health or hfe disturbed, but the dis- 

 turbance effected by the toxins is unessential to the regeneration of 

 receptors and the formation of haptines, as was shown by Ehrlich* 

 who found that when diphtheria toxin is kept, it undergoes a change 

 mto toxoids and loses its poisonous quality, though its haptophores 

 being unchanged, it still attaches to the receptors and stimulates 

 their regeneration, thus bringing about antitoxin formation, and also 

 still attaches to haptines when brought into contact with them by 

 mixing antitoxic serum and old toxin in titro. Further it has been 

 found by Metchnikoff that the cells of the central nervous system 

 * Klinisches lahrbuch, 1897. 



