102 THE PRINCIPLES OF IMMUNOLOGY 



diseases, but results are not so brilliantly successful as in secondary 

 anemias, particularly those resulting from acute hemorrhage. Ill 

 effects following transfusion are spoken of as reactions and include 

 fever, chills, cyanosis, hemoglobinuria, and even death. Cases com- 

 ing to autopsy show parenchymatous degenerations of solid organs, 

 marked congestion of all viscera, acute splenic hyperplasia, hemo- 

 globin staining, and sometimes multiple small emboli of agglutin- 

 ated erythrocytes. Blood studied in life has shown phagocytosis of 

 erythrocytes by the recipient's white corpuscles. The reactions de- 

 pend in large part on intravascular agglutination and hemolysis, 

 but probably certain other factors play a part. The prevention of 

 these other factors awaits the determination of their nature, but the 

 avoidance of agglutination and hemolysis can easily be accomplished 

 by use of the very simple tests for the determination of the presence 

 of conflicting iso-agglutinins. The simplest of these tests is the deter- 

 mination of the groups to which recipient and prospective donors 

 belong. The most desirable means of selection, in our opinion, is 

 that whereby the donor is chosen from the same group as the patient. 

 Lee and others have maintained that it is equally safe to use members 

 of Group I as donors for recipients of any group. The argument in 

 favor of this procedure is based on the statement that the real danger 

 in transfusion is the use of a donor whose cells are agglutinated by the 

 recipient's plasma and that the converse has little or no significance. 

 The cells of Group I are not agglutinated by any sera and are, there- 

 fore, safe to use. In our own experience we have seen occasional 

 reactions following this procedure and prefer to use a donor in the same 

 group as the recipient. Reactions following the general use of Group I 

 donors do not necessarily mean that the trouble is the result of agglu- 

 tination or hemolysis, for, as has been indicated above, other factors 

 may be concerned. Nevertheless, it holds true that thousands of trans- 

 fusions have been done with Group I as the " universal " donor and 

 without reaction. The explanation of the fact that a donor may thus 

 be used, whose plasma or serum is capable of agglutinating the recipi- 

 ent's erythrocytes in vitro, is not settled, but certain theories have 

 been offered. It must be remembered that in transfusion a small bulk 

 of blood is introduced, as compared with the total bulk in the recipi- 

 ent's body. Therefore, agglutinins introduced in this way are much 

 diluted, and as they ordinarily occur in low titer they may be sufficiently 

 diluted to be ineffective. Another possibility is that the agglutinins 

 are absorbed equally by an extremely large number of cells, each cell, 

 therefore, taking up too small an amount to be subjected to agglutina- 

 tion. A third possibility is that an excess of non-agglutinable cells 

 and the presence of the patient's own plasma permits of the formation 

 of only small clumps of cells, so small that they are of no significance 

 in the circulation. Our own work has failed to demonstrate anti- 

 agglutinins in a large number of tests, and it seems improbable that a 

 mechanism of this type operates to protect the recipient. It is conceiv- 

 able, however, that these possible factors of safety may not operate and 



