W. B. WHERRY 877 



activity of these cells. The disappearance of fibrin from the inflammatory exudate is 

 due in part to leukoprotease and in part to a proteolytic enzyme which acts best in 

 an acid or neutral medium. 



PROPHYLACTIC AND THERAPEUTIC IMMUNIZATION 



Prophylactic immunization we owe to Jenner and especially to Pasteur who ap- 

 plied Jenner's idea to the prevention of many diseases of man and animals. It was be- 

 lieved for many years that a living, attenuated virus was necessary in order to produce 

 immunity. The original plan of using an attenuated live virus for immunization 

 (chicken cholera, anthrax, etc. [Pasteur]) has been again revived by Calmette in im- 

 munization against tuberculosis.' 



The work of Ferran on cholera, of Haffkine on cholera and plague, and of Wright 

 on typhoid fever showed that immunity could be brought about by the injection of a 

 dead virus or antigen; by such means successful immunization has been practiced 

 against typhoid and paratyphoid fever, cholera, plague, Malta fever, bacterial dys- 

 entery, pneumonia, etc. By the use of toxins of bacteria, immunization has been ac- 

 complished against tetanus, diphtheria, gas gangrene, scarlet fever, eyrsipelas, etc. 



To Wright,^ however, we owe the conception that immunization may produce 

 therapeutic results even if undertaken after a pathogenic parasite has implanted itself 

 in the tissues of a host. The observations that suitably administered typhoid antigen 

 would lead to a thousand-fold increase in the bactericidal action of the blood, and an 

 increase in its opsonic power, and that this "epiphylactic" response could be measured 

 within twenty-four hours after injection of an antigen, together with reflection on the 

 fact that injection of plague antigen during the incubation period of the disease often 

 markedly benefited the patient, led to that idea — "The idea that the uninfected and 

 still inactive regions of the body can by applying the stimulus of a vaccine be made 

 to bring succour to the infected regions was, as you know, the mother- idea of vaccine 

 therapy,"^ 



This direct and logical outgrowth of Wright's studies should have led to the ful- 

 filment of his prophecy — "the physician of the future will be an immunisator" — but 

 bafiied by the difficulties and uncertainties of the opsonic technique and perhaps justly 

 fearing the dreaded "negative phase," the physician still fixes his eye on the chemical 

 and physical manifestations of disease and largely ignores the parasites whose de- 

 struction is the sine qua non to recovery. 



Briefly Wright's technique^ in performing the phagocytosis experiment consisted 

 in mixing in a capillary glass pipette equal volumes of a patient's serum, washed leuko- 

 cytes, and a homogeneous suspension of bacteria in physiological sodium chloride 

 solution. The mixture was then kept at body temperature for fifteen to thirty min- 

 utes, again mixed in order to obtain a uniform sample, and thin smears stained and 



' Calmette, A., Guerin, C, Negre, L., and Boquet, H.: Ann. de I'ltist. Pasteur, 40, 89. 1926. 



= Wright, A. E.: Brit. M. J., i, 1069. 1903. 



5 Wright, A. E.^ Colebrook, L., and Storer, E. J.: Lancet, i, 365. 1923. 



"i Wright, A. E., and Colebrook, L.: Technique of the Teat and Capillary Tube. London: 

 Constable, 1921. Jones, Carmalt: Introduction to Therapeutic Inoculation. New York: Macmillan 

 & Co., 1911. 



