64 IMMUNO-CATALYSIS 



In an extensive investigation on the antigen-antibody balance in 

 lobar pneumonia, Blake (1918) studied: (a) daily blood cultures 

 throughout the course of the disease; (b) daily determinations of the 

 concentration of soluble specific substance in the blood and urine, and 

 (c) daily determinations of agglutinins and precipitins in the blood 

 serum. All patients who failed to excrete soluble antigen in the urine 

 during the course of the disease developed precipitins in the blood at 

 or about the time of crisis, v\'hich may indicate that the development of 

 precipitin in the body keeps pace with the elaboration of the antigen 

 and that the two serve to neutralize each other until finally the develop- 

 ment of precipitin exceeds the formation of soluble antigens, and free 

 precipitin appears for the first time in the blood. Furthermore, the 

 concentration of precipitin, after rising rapidly during the period shortly 

 after crisis, fell rather abruptly coincident with the appearance of 

 soluble antigen in the urine. Apparently, according to Blake, this is 

 associated with the liberation of a considerable amount of antigen by 

 the resolution of the pneumonic consolidation. At least it was coinci- 

 dent with it. The fact that in two cases during this period small 

 amounts of precipitin in the blood and of soluble antigen in the urine 

 were simultaneously present, was explained as due either to antigen 

 and precipitin simultaneously present in approximately equal amounts 

 in the body and not in all instances completely bound, or that the 

 kidney possessed the power of separating the two, excreting the soluble 

 antigen and retaining the precipitin. The fact also that recovery was 

 invariably accompanied by the appearance of agglutinins was striking, 

 and suggested to him that here again a struggle between living antigen 

 (i.e., pneumococcus) and its corresponding antibody was taking place. 



On the other hand, in those cases, usually severely infected, in 

 which soluble antigen was excreted throughout the course of the 

 disease, and in which precipitin did not appear in a free state in the 

 blood, it appeared to Blake that the formation of precipitin never 

 equalled the elaboration of soluble antigen, which was constantly in 

 excess and readily excreted in the urine. He attributed his inability to 

 detect the presence of soluble antigen in the blood in these cases to 

 probable insufficient refinement of his method of testing. As will be dis- 

 cussed below, it may have been due to the constant neutralization and 

 removal of the soluble antigen by the antibody present in the blood 

 stream and excretion through the kidneys. It was also observed that, in 



