555 



THE PROBABLE IDENTITY OF THE OPSONINS WITH 

 THE NORMAL AGGLUTININS. 



By R. Greig-Smith, D.Sc, Macleay Bacteriologist to the 



Society. 



In the body fluids of animals there exist certain substances 

 which while exerting no bacteriolytic action, prepare bacteria for 

 inception by the mobile phagocytes. These were discovered by 

 Denys and Leclef,"^ but were apparently rediscovered by Wright 

 and DouglaSjt who named them opsonins. It is only after 

 bacteria have been subjected to the action of the opsonins that 

 they are ingested by the polymorphonuclear white blood cor- 

 puscles. The average number of bacteria englobed by a poly- 

 nuclear corpuscle can be used to indicate the relative amount of 

 opsonins in a serum. The opsonins appear to play an active part 

 in immunity. Their activity was specially noted by Wright and 

 Douglas in the susceptibility or non-susceptibility of individuals 

 towards invasion by the pyogenic staphylococci. The blood 

 serum of patients who were subject to boils, etc., was always 

 found to be low in opsonic power towards staphylococci compared 

 with the serum of normal individuals. By the regulated inocula- 

 tion of staphylococcus vaccine, a patient could be protected against 

 accidental invasion, and at the same time the opsonic power of 

 his serum rose above the normal. 



Blood serum can opsonisej a variety of bacteria. All the 

 bacteria tested by Wright and Douglas were ingested by the 

 mobile phagocytes after treatment with blood serum. These 



* Cent. f. Bakt. xxiv, 685 (also La Cellule, 1895). 

 t Proc. Roy. Soc. Ixxii. (No.483), 1903, p.357; and Ixxiii. (490), 1904, 128. 

 I A non-specificity does not appear to be claimed by Wright and Douglas 

 for the opsonins, as they always speak of "the opsonins." Bulloch and 

 Atkin, on the other hand, refer to "the opsonin," from which it would 

 appear that they consider there is only one, and that non-specific. 



