HEMAGGLUTININS 



273 



tination may be so marked as to prevent hemolysis unless the tubes are 

 frequently and vigorously shaken. 



Small amounts of normal hemagglutinins may be found. Of par- 

 ticular practical importance are those for animals of the same species, 

 the so-called isohemagglutinins. 



Isohemagglutinins were discovered independently by Landsteiner 

 and Shattuck in 1900, and were studied quite extensively by Hektoen 

 and Gay. At first the occurrence of isoagglutination was regarded as 

 of pathologic significance, but later researches showed that they may be 

 found in a large percentage of normal bloods. According to Land- 

 steiner and Hektoen, human bloods may be divided into four groups, as 

 follows : 



Group 1: Here the corpuscles are not agglutinated by any human 

 serum, whereas the serums agglutinate the corpuscles of the other groups. 

 This group includes about 50j>er cent, of all persons. 



Group 2 : In this group the corpuscles are agglutinated by the serums 

 of other groups, whereas the serums agglutinate the corpuscles of Group 

 3 but not of Group 1. 



Group 3: The corpuscles are agglutinated by all other serums, and 

 the serums agglutinate the corpuscles of Group 2 but not of Group 1. 



Group 4: The corpuscles are agglutinated by all other groups, but 

 the serums are unable to agglutinate any human corpuscles. These are 

 quite rare. 



The group characteristics are hereditary, and permanent throughout 

 life. 



With the increasing number of blood transfusions, the phenomena of 

 isoagglutination and isohemolysis the two being closely related are 

 of considerable practical importance, especially if the patient is suffering 

 with cancer, when the serum is likely to be actively hemolytic for the 

 donor's corpuscles. 



In selecting the donor for a transfusion, agglutination and hemolysis 

 tests should always be made before operation if time permits. The 

 tests made in vitro are usually safe guides as to conditions existing in 

 vivo, and such preliminary tests may prevent the occurrence of untoward 

 symptoms associated with intravascular hemolysis or agglutination, 

 such as fever, dyspnea, edema, and hemoglobinuria. As a rule, the 

 donor selected should be a near relative, and whenever time permits, a 

 Wassermann reaction and the isoagglutination and isohemolysin tests 

 should be made. That donor should be chosen whose blood shows no 

 inter-agglutination or hemolysis with the patient's serum and corpuscles. 

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