isohemagglutinins 181 



Presence of Subgroups Does Not Interfere with Routine 

 Typing. — Since the a' agglutinin is almost always found associated 

 with the a agglutinin in sera and the A' agglutinogen likcAvise 

 associated with the A agglutinogen, it is evident that their exist- 

 ence does not invalidate any conclusions as to blood grouping 

 based upon the postulates of Landsteiner. In other words, their 

 presence cannot be detected by the routine method of typing, 

 but is detected only hy means of absorption experiments. 



Irregular Ag-g-lutination. — Landsteiner and Levine (1929) have 

 made an extensive study of "isoagglutinin reactions of human 

 blood other than those defining the blood groups." They cite the 

 observation of Thomson (1928) that in five out of 3,500 bloods ex- 

 amined he definitely proved an absence of isoagglutinins from 

 sera of bloods belonging to groups 0, A, and B. In this series 

 he observed 32 abnormal sera. Outherie and Huek (1924-25) 

 found one serum of group B which contained only an agglutinin 

 for one subgroup of A. In 1926, Landsteiner and Levine noted 

 two sera of bloods belonging to group AB that contained an a 

 agglutinin. 



Importance of Temperature. — In later studies (1929) they used 

 very sensitive tests by employing diluted blood (2.5 per cent) 

 and temperatures of 20°, 25°, 30° and 37° C. Most of the abnor- 

 mal reactions occurred at temperatures below 37° C. At the 

 latter temperature the abnormal agglutination either did not 

 occur or it disappeared when cells agglutinated at 20° C. were 

 warmed to 37° C. Landsteiner and Levine state that "for sev- 

 eral sera the upper limit of activity was at 30° C, for others at 

 25° or even 20° C." In all they examined 500 sera. They found 

 three sera of group AB that contained a' agglutinin, two sera of 

 group AB and one of group A that agglutinated intensely group 

 cells and to a lesser degree cells belonging to subgroup A.. 

 They further state that "in a total of about 500 sera examined 

 there were at least 16 that gave reactions designated as +, i.e., 

 about 3 per cent. Of 180 sera 12 or 6.6 per cent reacted weakly 

 and 31 sera (about 17 per cent) showed traces of agglutination 

 within the same group." They conclude that "one can speak of 

 abnormally reacting sera but hardly of abnormal blood cells." 



M, N, and P Factors of Human Blood. — In 1928, Landsteiner 

 and Levine demonstrated, by means of immune sera, three new 



