ANTITOXIC AND ANTIMICROBIC SERA. 



121 



is given off while the bacterium is alive; and in other instances the toxin 

 is intracellular and is o ily given off when the bacterium disintegrates; 

 consequently, an antimicrobic serum may cause the liberation of toxin. 

 Diphtheria, tetanus or botulism antisera are instances of antitoxic 

 sera, while practically all others are antimicrobic. There is but one 

 factor to consider in an antitoxic serum and that is the protoplasmic 

 particles which are thrown 

 off from the cell in response 

 to the injury incident to the 

 attack upon the cell by the 

 toxin particles. This free 

 particle in the circulation 

 represents the entire 

 mechanism of antitoxic im- 

 munity. It is capable of 

 uniting with the toxin mole- 

 cule and neutralizing its 

 toxic power, or rather so 

 binding its combining end 

 (haptophore group) that it 

 is incapable of attaching 

 itself to a cell, so that the 

 poisonous end of the toxin 

 (toxophore group) cannot 

 have access to the cell. In 

 antimicrobic sera we have 

 two factors to consider, the 

 first is a protoplasmic par- 

 ticle quite similar to the anti- 

 toxin molecule, but which in itself has no power of injuring its specific 

 bacterium. This particle is generally referred to as the amboceptor 

 or immune body. It is the specific product of the activity of a specific 

 bacterium or foreign cell against the body cells attacked. It with- 

 stands a temperature above 56 C. and of itself is incapable of injuring 

 the bacterium in response to whose attack it was produced. The 

 second factor in the bacteriolysis of the specific bacterium, or the 



FIG. 45. Receptors of the second order and 

 of some substance uniting with one of them. 

 (Journal of the American Medical Association. 

 1905. P. 1113.) 



c, Cell recepto: of the second order; d, tox- 

 ophore or zymophore group of the receptor; 

 e , haptophore of the receptor; /, Food substance 

 or product of bacterial disintegration uniting 

 with the haptophore of the cell receptor. 



