430 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



properties of the protein molecules and of the structures that can be 

 prepared from them under controlled conditions. 



In 1899 the late Sir William Hardy left the field of histology and 

 developed colloid chemistry in the belief that fundamental advances 

 in our knowledge of the structure of living tissue would have to await 

 advances of our knowledge of the molecules of which it is composed. 

 The time would appear to be at hand when the knowledge of the pro- 

 teins which Hardy next studied had reached a point where their study 

 in the solid state could form the basis of a new chemical morphology. 



THE BLOOD-GROUPING GLOBULINS (ISOAGGLUTININS) OF HUMAN 



PLASMA 



The dangers of transfusion with human blood have largely been 

 eliminated by our increasing knowledge of specific differences in the 

 red blood cells of different individuals. Landsteiner reported in 1900 

 the presence of agglutinogens in red cells and the corresponding 

 isoagglutinins in human sera. Our present classification of blood 

 types and of red cells distinguishes groups O, A, B, and AB. Other 

 studies have revealed in addition subgroups of type A and AB cells, 

 among them A 2 cells and A 2 B cells. The proportion of the individuals 

 in a population belonging to each blood group is approximately as 

 shown in table 5. 



The cells of group O blood are not agglutinated by either anti-A or 

 anti-B serum. The blood of such donors is therefore recommended for 

 whole-blood transfusion in military medicine, since no reaction 

 normally occurs regardless of the type of the recipient. 



The sera of O type blood as well as of A and B type blood contain 

 isoagglutinins, however. If the plasma of O blood is mixed with the 

 proper proportion of B cells, the anti-B isoagglutinins are removed, 

 leaving the plasma rich in anti-A isoagglutinins. The plasma, or 

 serum, of group B bloods is of course also rich in anti-A isoagglutinins, 

 the plasma or serum of type A blood in anti-B isoagglutinins. 



Table 5. — Distribution of population among blood groups 



(Computed from various sources for the population of the United States] 



Group of red blood Approximate fre- Blood-grouping globulins present in plasma ' 



cells quency percent 



45 Anti-A, Anti-A,, Anti-B. 



B 



A, 



A 2 



AjB 



A 2 B 



* Omitting certain rare isoagglutinins. 



