TOXOIDS 75 



Haptophile Group. The side-chain of the cell to which the toxin 

 becomes attached. 



Toxophore Group. The side-chain of the toxin which has the 

 poisonous effect. 



Toxophile Group. The side chain of the cell to which the toxo- 

 phore group of the toxin becomes attached, and by which attachment 

 the damage is done. 



Receptors. Side-chains of the cells which unite with the side- 

 chains of the toxins are also called by a general term, the cell recep- 

 tors. It must be assumed that the attachment of the side-chains of 

 the toxin to the cell receptors destroys the latter, at least, so far 

 as their character and existence as side-chains are concerned. It is 

 a general observation in pathology that the destruction of physiologic 

 parts is always followed by an attempt on the part of the organism 

 to replace what has been lost. So if any liver or kidney cells have 

 become necrotic the organism tries to replace them by new cells; 

 this is called a regeneration. Very frequently an attempt at regen- 

 eration leads to the production of an excess of that which had been 

 lost. 



The side-chain theory assumes that whenever cell receptors have 

 been made useless by toxins the cell not only replaces the lost recep- 

 tors but that it produces them in great excess. So great does this 

 excess become that the cell body cannot retain all the new receptors 

 or new side-chains, and it must expel a large number of them into 

 the blood serum and other juices of the body. If an animal which 

 possesses a large number of such receptors in its blood serum becomes 

 infected a second time by the same toxin, what occurs? Clearly, 

 before the toxins have a chance to attach themselves to the cells they 

 are caught, as it were, by the free floating receptors which prevent 

 them reaching the cells and render them harmless. Thus the animal 

 is protected against them. A serum full of free receptors which will 

 catch and unite with the toxins is called an immune serum or an 

 antitoxic serum. In fact, the free receptors are the antitoxin which 

 unites with the toxin to protect the cells. 



Toxoids. It has been stated that the toxin possesses a hapto- 

 phore and a toxophore group. This can be shown by the observation 

 that solutions of toxins after some time lose much or all of their poi- 

 sonous properties, and yet these poisonless non-toxic toxins may 

 still be able to anchor themselves to cells and cause the formation of 

 free receptors. In other words, they can still be used to manufac- 

 ture an antitoxic immune serum in the body of an animal. The 

 toxin has lost its toxophore side-chain or group, but it still possesses 

 its haptophore side-chain or group. Such a toxin is called a toxoid. 

 Ehrlich has introduced into the nomenclature of serum investigation 

 the two symbols L and L + . The letter L stands for the term lethal 

 (deadly, fatal). The former symbol L designates a toxin-antitoxin 

 mixture which is completely neutralized, and therefore will not kill 



