OPSONINS TROPINS BACTERIAL VACCINES 169 



EXAMPLE. 



Bacteria in Bacteria per 



100 leukocytes. leukocyte. 



Staphylococcus suspension + pooled serum and 



leukocytes 750 7.5 



Staphylococcus suspension + patient's serum and 



leukocytes 250 2.5 



2 5 

 Opsonic index, patient's serum = ^-^ or 0.33 per cent. 



7.5 



Numerous observers have been unable to obtain uniform results 

 with the technic of Wright for opsonic index determination, and this 

 is not surprising when the many variable factors entering into the 

 method are reviewed. Attempts have been made to eliminate or 

 limit the variable factors: Simon proposed a dilution method in 

 which the pooled and patient's serum are diluted 1 to 10, 1 to 100, 

 etc., before incubation with the bacteria and leukocytes. That dilu- 

 tion of serum at which phagocytosis practically ceases in the normal 

 and patient's serum respectively is taken as a basis for comparison. 

 Inasmuch as the opsonic index is rarely determined as a guide for 

 treatment of bacterial disease with bacterial vaccines at the present 

 time, however, a discussion of these modifications, which are too 

 involved for practical use, is left for more pretentious volumes. 



The Nature of Opsonins. There appears no doubt that the hypo- 

 thetical substance or substances called opsonin by Wright exist in 

 normal sera, and it is equally certain that they may be diminished 

 during infection. Furthermore, opsonin may be increased either in 

 amount or in potency by careful immunization. The relation of 

 opsonins to other antibodies, normal or specific, is a subject of con- 

 troversy at present. The researches of Neufeld and Rimpau, 1 Hek- 

 toen 2 and others indicate that the normal opsonins those of normal 

 sera are thermolabile, but those developed during immunization 

 to a specific organism bacteriotropins are relatively thermos tabile. 



It has been suggested that opsonins or bacteriotropins are not to 

 be distinguished from other immune bodies as normal and specific 

 amboceptors or agglutinins. The rapidity with which the opsonic 

 index may be increased or diminished within a few hours following 

 injections of bacteria, however, would suggest a possible distinction 

 between these antibodies and the slowly developing specific bacteri- 

 cidal and agglutinating antibodies. 



Vaccine Therapy. The value of vaccines and of autogenous vac- 

 cination in bacterial prophylaxis and bacterial immunization as set 



1 Deutsch. med. Wchnschr., 1904, 1458. 



2 Jour. Inf. Dis., 1906, iii, 434; 1909, vi, 78; 1913, xii, 1. 



