148 NINTH REPORT. 



PROTECTIVE AND CURATIVE ARTIFICIAL IMMUNITY AS BASED 



ON THE THEORY OF OPSONINS. 



A. P. Ohlmacher, M. D. 



Artificial immunity, especially the protective immunity induced by the 

 use of bacterial products, is a subject of practical- concern to sanitarians. 

 Artificial immunity extended to the conquest of already existing disease is 

 likewise a topic of timely interest to sanitarians, and to mankind in general. 

 With your permission I shall therefore discuss briefly a recent and most prom- 

 ising phase of immunology as applied both to the prevention and treatment 

 of diseases caused by pathogenic microparasites, and in doing this I shall 

 request the privilege of waiving as far as possible the very involved theoretic 

 controversies in which recent immunology has become involved and bring 

 you at once to the comparatively simple hypothesis underlying the work of 

 Sir A. E. Wright and his associates which, even at this relatively early day 

 in its develo]:)ment, promises advantages of momentous importance. I re- 

 fer to Wright's method of bacterial inoculation, either protective or curative, 

 as founded on the theory of opsonins, which, after a period of latency most 

 unusual in these days of ready publicity, has abruptly sprung into very 

 great prominence in the English speaking medical world. 



The expression "founded on" the theory of opsonins must, however, be 

 somewhat qualified, for it is a fact that Wright's early work in bacterial in- 

 oculation by which the basis for his present practice was established, was 

 successfully prosecuted before Wright and Douglas demonstrated the exist- 

 ence of so-called "opsonin" in the blood serum. And this preliminary 

 work was in the line of protective artificial immunity, the problem being 

 the successful production of immunity against typhoid fever with which 

 Vv'right in his position as pathologist to the Army Medical School at Netley 

 laboriousl}^ engaged himself. These anti-typhoid inoculations, or as they 

 are miscalled "vaccinations," were performed along lines already laid down 

 with more or less success by Haffkine in his anti-cholera and anti-plague in- 

 oculations, and while considerably modified in method, rested on the prece- 

 dents established in protective vaccination against smallpox, hydrophobia, 

 anthrax, rinderpest, bovine pleuro-pneumonia and several other diseases. 

 The particular point in the procedure on which Wright laid stress, aiul 

 which has characterized his later technique, was the use of dead ])acterial 

 suspensions as the source of his inoculating medium, the vitality of the ty- 

 phoid bacilli being destroyed by heating one hour at 60 °C, which was effect- 

 ive in attaining tJhe end sought and still did not, a])parently, destroy those 

 bacterial substances which were required to produce the desired effect. 

 Today this procedure is generally in vogue in the preparation of the various 

 bacterial inoculations required in treating infectious diseases according to 

 the method of opsonic therapy. 



Studying the effect of his anti-typhoid inoculations Wright at first at- 

 tempted to gage these by using the agglutination test and for a time it ap- 

 peared that reliance might be placed on the results. Not finding these satis- 

 factory he next resorted to a method of measurement based on the bacteri- 

 cidal property of the serum of inoculated individuals. After perfecting a 



