70 VACCINE AND SERUM THERAPY. 



and subsequent injection is not always controlled, even by Wright 

 and his pupils, by the opsonic index. 



In accepting opsonins as important factors in immunity other 

 immune substances must not be lost sight of. Various investi- 

 gators have designed methods by which the action of agglutinins 

 and bacteriolysins is' to be inhibited, so that opsonic indices may 

 be determined and used as a guide for the dosage and inter-spac- 

 ing of injections. The justifications for such regulation of dosage 

 and determination of the proper time for injection is not evident. 

 In a patient suffering with cerebro-spinal meningitis, from the 

 spinal fluid of which Mic. meningitidis was cultivated, the writer 

 tried to govern the dosage and inter-spacing of injections of 

 meningococcus vaccine by the opsonic index. After three to 

 four minutes of incubation of the mixture of leucocytes, men- 

 ingococcus suspension and patient's serum, all of the organisms 

 were found to be dissolved. It is evident that lysins in this case 

 were probably of more importance in immunity than were opso- 

 nins. Clark has proposed that in determining the opsonic index 

 of serum of typhoid patients, the serum be heated to 56 C. in 

 order to destroy the lysins for the typhoid bacillus. By follow- 

 ing out this method Clark finds that relapses follow upon a drop 

 in the opsonic index. How much more important would it prob- 

 ably be to determine the curve for lysins in a case where lysins 

 are present in such amount that it is necessary to destroy their 

 action before opsonic index deternr nations can be made? This 

 would seem more rational, especially because our knowledge con- 

 cerning lysins in immunity is greater than it is concerning opsonins, 

 which may or may not play any part in immunity. . 



According to the determinations of the opsonin content of 

 the blood, Wright and his pupils have found that the opsonic 

 index begins to rise two to five days after injection, and usually 

 reaches its height after about five to eight days. In most cases 

 adherents of the opsonin theory make injections every four to 

 eight days. The appearance in the blood, however, of the better 

 known anti-bodies comes somewhat later. Bacteriolysins are 

 found to be present at times in the spleen twenty-four hours after 

 injection of culture. They do not, however, appear in quantities 

 in the blood until five to nine or fourteen days later. Agglutinins 

 are found to be present in the blood from eight to twelve days 



