BLOOD GROUP ANTIGENS 95 



derivatives. Removal of these sugars by dialysis makes Bauhinia 

 purpurea extracts nonspecific; that is, they then agglutinate human 

 blood irrespective of blood group. The effect of certain sugars on 

 such nonspecific Bauhinia extracts is shown in Table 7-4. 



It vv^ill be seen that the nonspecific activity of Bauhinia extracts 

 is inhibited by sugars of Makela's group 2. It may even be that the 

 red cell receptor detected by nonspecific Bauhinia extracts is the 

 same as that detected by other plant agglutinins which are inhibited 

 by group 2 sugars. No adequate comparison has yet been made.* 

 From the inhibiting power of the disaccharide, trisaccharide, and 

 tetrasaccharide containing galactose, it can be assumed that the 

 Bauhinia receptor is an oligosaccharide containing at least one more 

 unit beyond galactose. It probably contains several monosaccharide 

 units, although, if it does, one can conclude that the next-to-terminal 

 unit is not galactose, as in stachyose, for this sugar is not a very good 

 inhibitor here. Although the Bauhinia receptor has some features 

 in common with the B receptor, it is obviously not identical with 

 it since it occurs in all human erythrocytes. As a matter of fact, 

 B substance does not react with the Bauhinia agglutinin. 



Peanut Receptor 

 Another receptor has been detected with the aid of extracts of 

 ordinary peanuts. This plant agglutinin is also inhibited by sugars 

 of group 2 (Table 7-5). That galactose is the most effective monosac- 

 charide inhibitor suggests that galactose is the terminal group of 

 this receptor also. The receptor consists of more than one sugar 

 unit, however, since two disaccharides, trehalose and lactose (the 

 former not even containing galactose), inhibit better than galactose. 

 Two other disaccharides containing only glucose (maltose and cel- 

 lobiose) also inhibit well. The inhibitory power of the three all- 

 glucose disaccharides and the fact that lactose contains glucose sug- 

 gest that glucose may be the next-to-terminal group in the peanut 

 receptor. This is supported by the observation that glucose itself 

 has some inhibiting power. The effectiveness of trehalose suggests 



* In my laboratory we have recently made a detailed comparison of two 

 lectins that are inhibited by group 2 sugars (those from BauJiiiiia purpurea 

 and Ricinus communis) , and obtained evidence that the two receptors are not 

 identical (Boyd and Waszczenko-Zacharczenko, 1961). 



