840 GEOEGE K. MINOT AND ARLIE V. BOCK 



The severity of the reaction may vary greatly not only in different 

 patients, hut also in the same patient, even when the same donor is used 

 for a subsequent transfusion. A mild reaction following a first trans- 

 fusion may consist of but a very temporary rise of temperature and a 

 chill. On the contrary, a second transfusion from the same donor may 

 induce a severe hemolytic reaction. A presumptive explanation for this 

 change in reaction is the development in the interim between the trans- 

 fusions of an increase in strength of the agglutinins and the development 

 of hemolysins in the patient's blood. 



2. Reactions Not Due to Recognized Incompatibility. These are 

 of two types. First, those that are distinctly rare and that resemble an iso- 

 hemolytic reaction. Second, those that are the commonest and mildest re- 

 actions that follow transfusion, and that are associated with the instability 

 of blood when removed from the body. 



(a) Reactions That Resemble Those Due to Recognized Iso-hemr 

 olysis. In some diseased conditions, particularly sepsis and blood dis- 

 eases, the blood sometimes seems to be altered with a production of 

 hemolysins and agglutinins not normally present. To these abnormal 

 hemolysins and agglutinins are attributed some of the rare reactions of a 

 hemolytic nature which may be fatal following transfusion performed 

 with donors selected by the usual tests. Such reactions appear to be 

 delayed usually some hours in their onset in contrast to the classical iso- 

 hemolytic reactions that develop at least shortly after transfusion. (See 

 Bowcock, and Robertson and Rons.) 



Sydenstricker, Mason and Rivers have observed serious hemolytic re- 

 actions following repeated transfusion in pernicious anemia, when the 

 donors were properly chosen. The cause of these reactions is unknown. 

 These hemolytic reactions associated with properly tested donors are not 

 to be confused with true iso-hemolytic reactions dependent upon improper 

 agglutination tests. Some hemolytic reactions that have been reported 

 when the donor's and patient's blood was tested, undoubtedly have been 

 due to improper laboratory tests. The tests were probably incorrectly 

 read owing to the presence of weak agglutination reactions in vitro. 



(b) Reactions Associated with Instability of Blood When Removed 

 from the Body. The commonest reactions seen after transfusion cannot 

 be foretold and they are not definitely associated with agglutination or 

 hemolysis. These reactions are of a milder nature than those previously 

 described though they rarely may be distinctly severe. The onset of 

 symptoms is usually about an hour after transfusion. In the majority of 

 cases they subside within twenty-four hours. The symptoms usually begin 

 with a sharp rise of temperature of a degree to four or five degrees, and 

 even more. With the symptoms of fever, nausea, vomiting and diarrhea 

 may occur. Chills may be associated with temperature rise. Urticaria, 

 and other lesions of the erythema group, and rarely edema and purpura, 



