144 IMMUNOLOGY 



Alpha Lysins. — Between the years of 1888 and 1890, Nuttall in 

 England and von Fodor on the Continent published their investiga- 

 tions as to the germicidal property of blood. By mixing defibrin- 

 ated blood with bacteria and plating out after a period of incuba- 

 tion, they were able to show that some defibrinated bloods pos- 

 sessed mild germicidal properties. This seemed to be lessened or 

 destroyed by heating to 60° C. for a short time or by standing for 

 a longer time at room temperature. 



These observations were confirmed by Buchner (1889) who re- 

 garded the germicidal property of blood as due to an unstable, 

 thermolabilc substance which he called alexin. By animal in- 

 oculation experiments, he showed that bacteria were destroyed 

 by humoral elements in serous cavities of the body and in the 

 subcutaneous tissues. Buchner conceived of resistance as due to 

 alexin. This thermolabilc bactericidal substance is also called 

 alplui lysin. 



Immune Lysins and Pfeiffer's Phenomena. — In 1894 Pfeiffer 

 was studying cholera immunity and noted that when those guinea 

 pigs which recovered from infection with Microspira comma were 

 reinoculated intraperitoneally, the bacteria were rapidly destroyed 

 and the animals survived, whereas in normal pigs very little de- 

 struction of the organisms occurred and the animals succumbed. 

 Pfeiffer made three other observations that are fundamental to 

 our present concepts. He found first, that the immunity enjoyed 

 by the recovered pigs was specific for cholera vibrios and not for 

 other bacteria; second, he could convey this immunity to normal 

 animals by injecting intraperitoneally a small amount of blood 

 from immune animals together with the virulent vibrios; third, 

 Pfeiffer found that heated immune serum when injected together 

 witli the vibrios was effective in protecting tlic normal pigs. This 

 WAS quite puzzling since he had previously confirmed Buchner s 

 conclusions that in test tube and plating experiments, heated 

 serum or defibrinated blood has apparently lost its germicidal 

 property. Pfeiffer' decided that some substance from the endo- 

 thelial cells lining the peritoneum was able to restore to heated 

 serum its germicidal property. 



Pfeiffer's Immunity Unit. — It is interesting to note that 

 Pfeiffer realized the importance of devi.sing some method for 



