14 



between one "Type" and another and (2) the extremely wide 

 range of antigenic differences to be found amongst the " atypical " 

 strains. 



Leucocytes as an Adjuvant for Immunisation. 



Is it possible to improve the value of a serum by employing 

 some adjuvant along with the pneumococci used for immuni- 

 sation ? 



Some slight support to this suggestion is afforded by the work 

 of Alexander.* Observing that, in human pneumonia, serum 

 taken about the time of the crisis often has some protective power, 

 and that therefore it is possible for the living body to elaborate 

 protective substances within a short time, he tried to find a 

 rapid method of producing immunity in rabbits. The adjuvant 

 which he tried was rabbits' leucocytes. He worked with Type II 

 pneumococci and Type II immune horse serum, both obtained 

 from the Rockefeller Institute. His cultures were washed in 

 saline and sensitised by adding excess of immune serum, pre- 

 cipitation being apparently complete in about 4 hours. The 

 serum was removed by centrifugalisation and the cocci were 

 then emulsified in saline. The cocci and an emulsion of leuco- 

 cytes were mixed together and incubated in a water-bath at 

 37° C. for 6 to 8 hours. 



Unsensitised cocci, after incubation with leucocytes, and also cocci 

 which wore sensitised but not incubated with leucocytes, were too virulent 

 to use in large doses. Cultures treated by his method were attenuated 

 but did not lose their vitality. The cocci and leucocytes ought not to be 

 incubated for more than 6-8 hours. When he incubated them for 1 1 J hours 

 the rabbits became ill and died. 



The injections were made intravenously. A rabbit received 

 3 injections, on successive days, of 1,000 million cocci and 

 100 million leucocytes. Blood was taken 5 days after the last 

 injection and it was found that 0-2 c.c. of the serum protected 

 mice against 0-001 c.c. of culture, 0-000 000 01 c.c. being fatal 

 to the control. He tried to increase the amount of protective 

 substance by giving rabbits three series of injections, but did 

 not succeed. He also tried the effect of treating his sensitised 

 cocci with leucocytic extract instead of whole leucocytes but the 

 results were less uniformly successful. When both leucocytes 

 and sensitised cocci were thoroughly washed to get rid of all 

 traces of serum, the results were irregular, apparently because 

 traces of free serum assisted the action of the leucocytes. 



The Work of Preston Kyes. 



An entirely new aeparture in serum therapy has been made 

 by Preston Kyes, who has endeavoured to cure human pneumonia 

 by treatment with serum obtained by inoculating fowls. It is 

 difficult to explain his results, or to appraise their exact value ; 

 his work is worth quoting because it is just possible that his 



* Journ. Med. Res., XXXVII, p. 471. 191& 



