96 IMMUNOLOGY 



particulate matter makes it possible for leucocytes to engulf them 

 more readily. As will be shown in another chapter there is a great 

 deal of evidence indicating that when immune serum is mixed with 

 homologous bacteria the latter specifically adsorb antibody protein 

 (globulin) on their surfaces and that this film of globulin becomes 

 insoluble in salt solution (denatured). This probably constitutes 

 the process called opsonification or preparation of the cell for 

 phagocytosis. Natural antibody acting in this manner is called 

 opsonin while similarly acting antibody in an immune animal is 

 called ' ' bacteriotropin. ' ' 



Some of the earliest investigations of the role that antibodies 

 play in the process of phagocytosis were carried out by Denys 

 and Leclef (1895), Mennes (1897), and Marchand (1898). They 

 showed that immune serum increased phagocytosis and thought it 

 was due probably to some action on the bacteria. According to 

 Muir (1931) particulate matter such as charcoal, flour, powdered 

 albumin, milk globules, and other materials, adsorb serum proteins 

 and become nonspecifically opsonized. 



In 1903, Wright and Douglas carried out an extensive investiga- 

 tion of the whole question and concluded that certain immune 

 bodies which they called opsonins acted upon the bacteria and 

 rendered them more susceptible to phagocytosis. In this work 

 they used a modification of Leishmann's (1902) technique of study- 

 ing phagocytosis. They concluded that normal opsonins are in- 

 activated at 60° C. for fifteen minutes. In 1904, Neufeld and 

 Rimpau discovered that immune opsonins are heat stable. They 

 consider this an important difference between them and normal 

 opsonins. Bullock and Western (1906) and Hektoen (1908) 

 showed that normal opsonins could be specifically adsorbed and 

 Chapin and Cowie (1907) showed that inactivated opsonin could 

 be reactivated. This suggested that it was quite similar to Bordet 's 

 sensitizer or Ehrlich's amboceptor. 



Role of Complement. — Dean (1905, 1907) and others have 

 shown that even the activity of immune opsonins (named bac- 

 teriotropins by Neufeld) is materially increased by normal serum 

 containing complement. Sleeswijk (1908) concludes that both 

 normal and immune opsonins have dual structiires in that the 

 activity of both is increased by complement. He suggests that 



