9o6 THE HUMAN BLOOD GROUPS 



The technique just described (test tubes or slides) is to be recommended also for the direct 

 matching and will reveal even slight reactions. 



The following expeditious method for the direct matching advised by Coca renders the 

 separation of serum unnecessary. It is adapted to the selection of suitable universal donors 

 and to the detection of such as have exceptionally active agglutinins. 



Three or four drops of patient's and donor's blood are defibrinated in two tubes. Physi- 

 ological saline solution is drawn up to the 0.5 mark of a white-cell-counting pipette. The 

 recipient's blood is then drawn up into the pipette, until the upper level of the salt solution 

 is at the "i" mark. This is expelled upon one end of a glass slide and thoroughly mixed, 

 constituting ten divisions of 50 per cent patient's blood. The pipette is rinsed with saline 

 and, in the same way as just described, ten divisions of 50 per cent donor's blood are expelled 

 upon the other end of the slide. Two divisions of this 50 per cent donor's blood are carried 

 over to the ten divisions of the 50 per cent recipient's blood with which they are well mixed. 

 (Avoid bubbles.) The mixture is covered with a cover slip and clumps are looked for with 

 a microscope (low power) ; it Is kept under observation for fifteen minutes. 



It is recommended by some authors as an additional check that a small amount 

 of blood be injected first and the transfusion continued only if no untoward symptoms 

 develop. 



Aside from the agglutinin tests a thorough general examination of donors is 

 essential, including blood counts and the Wassermann reaction. Mention should be 

 made of the possibility of transmitting allergic conditions and malaria. 



With proper preliminary compatibility tests made and performed by experienced 

 men, transfusions are almost free of danger, and several authors report series of 

 hundreds of transfusions without any serious accident (Beck/ De Pemberton^). 



The instances reported of severe transfusion reactions in spite of apparently satis- 

 factory compatibility tests must be viewed with caution, as is exemplified by a recent 

 communication of Forssman and Fogelgren.^ 



Excluding faulty serological tests and inadequate surgical technique, there still re- 

 main a certain number of post-transfusion reactions such as chills, fever, and skin 

 manifestations which are of mild character in most cases. Various reasons have been 

 ofifered to explain the occurrence of these symptoms, viz., extravascular blood 

 changes, the effect of citrate, individual variations of the leukocytes (Doan),'^ the 

 serum proteins (cf. Hooker and Anderson), ^ and differences of the red cells not de- 

 tected by the usual isoagglutination tests. With regard to the agglutinin reactions 

 noticeable only at low temperature there is no definite proof as yet that these are of 

 significance for the outcome of a transfusion. Until such evidence is available it 

 would not seem indicated to resort on that account to a considerable complication of 

 the serum tests (cf. Unger,'' Guthrie and Pessel^). 



That in general there will be differences between donor and recipient follows from 

 the facts discussed above (p. 902). This consideration may have a bearing on the 

 results of repeated transfusions in man, in view of the possible formation of immune 



' Beck, A.: Miinchen. vied. Wchnschr., 74, 398. 1927. ^ de Pemberton, J.: loc. cil. 



3 Forssman, J., and Fogelgren, G.: Klin. Wchnschr., p. 1663. 1927. 



4 The individual difTerences between leukocytes found by Doan with the supravital stain do 

 not follow the group rule for erythrocytes. See Doan, C. A., J .A.M. A., 86, 1593. 1926. 



5 Hooker, S. B., and Anderson, L. M.: loc. cit. * Unger, L. J.: loc. cit. 

 ' Guthrie, C. G., and Pessel, J. F.: Bull. Johns Hopkins Hosp., 35, 23- 1924. 



