EMPLOYMENT OF BLOOD SERUM 267 



was from persons who had the disease at more remote periods, and the 

 third group from persons who, so far as they knew, had never suffered 

 with whooping-cough. The stage at which the treatment was given 

 was about the same in the three groups and the dosage depended upon 

 the body weight of the patient, varying between 40 c.c. and 125 c.c., 

 divided into two, three or four doses and injected into the gluteus 

 muscles. In the first group there were no deaths and no complications, 

 and the course of the disease was in no definite way different from 

 the usual course. The second group showed quite as satisfactory im- 

 provement as in the first group. In the third group there were two 

 pneumonia cases with one death and one case which apparently was 

 favorably influenced by normal serum treatment. The groups are so small 

 and the difference so slight as to give no reason for regarding this 

 mode of treatment as particularly effective. Vaccine treatment of this 

 disease gives much greater promise of success. 



During the recent great epidemics of so-called influenza, conva- 

 lescent serum was used in a considerable number of cases which 

 developed pneumonia. In many instances there was marked improve- 

 ment, but there is no clear indication that the results were specific or 

 that they depended absolutely upon the serum treatment. 



SERUM THERAPY IN INFECTIONS OF UNDETERMINED ETIOLOGY 



Introduction. The preparation of the immune sera discussed above 

 depends not only upon knowledge of the etiological agent of the disease 

 concerned but also necessitates the isolation of the organism in pure 

 culture. Several infectious agents are known to exist in blood and 

 tissues, since the diseases may be transmitted by means of inoculation 

 of blood, organs or organ extracts. Many of these agents are so small 

 as to pass through porcelain filters and are spoken of as the filterable 

 viruses. Some of these viruses have been observed to contain minute 

 globoid bodies which have been obtained in pure culture, but under 

 such conditions that they have not served well as antigens for the 

 production of immune sera. If immunization be attempted by injec- 

 tions of the blood or tissues containing the infective agents, the result- 

 ing immune serum contains not only antibodies for the infective agent 

 but also for the tissues. If these tissues happen to be from the same 

 species into which the serum is to be injected the hemagglutinins, 

 hemolysins and cytolysins in the immune serum may seriously damage 

 or even kill the individual so treated. Active immunization by the use 

 of infected tissues appears to progress favorably in spite of the presence 

 of the tissues, as seen in the active immunization of man and other 

 animals by the use of the virus of rabies* contained in the dried spinal 

 cords of rabbits. It is in the production of sera for passive immuniza- 

 tion that the danger from simultaneously formed tissue antibodies ap- 

 pears. Rous, Robertson and Oliver have studied this problem with a 

 view to removing from the immune serum these harmful elements. 

 After the immune serum is prepared the tissue antibodies are removed 

 by selective absorption with red blood-corpuscles, since these cells re- 



