30 G. LEJEUNE-LEDANT 



In conclusion, all parts of these experiments demonstrate that 

 all the transplantation antigens — both living cells and cell-free 

 extracts — will ehcit the formation of haemagglutinins in the 

 blood of recipients, provided that a sufficient antigenic stimulus is 

 given. 



B. Inhibition of the haemagglutination reaction by trans- 

 plantation antigens 



Since the previous experiments have demonstrated that all the 

 transplantation antigens tested lead to the formation of serum 

 antibodies (recognized by their abihty to agglutinate the red cells 

 of the donor) it seemed logical to assume that the same trans- 

 plantation antigens should be able to absorb these agglutinins, and 

 consequently inhibit the haemagglutination reaction. 



We (Albert and Lejeune-Ledant, 1959) were specially interested 

 by the suggestion that transplantation antigens belong to the 

 category of "mucoids" and perhaps are very similar to the blood 

 group substances (Billingham, Brent and Medawar, 1958). 

 These authors pointed out that transplantation antigens are 

 inactivated by Trichomonas foetus enzymic action and by periodate, 

 both well known to inactivate the blood group substances. These 

 blood group substances are detected and selected by the haemag- 

 glutination inhibition test. 



The use of extracts prepared by the various techniques used for 

 the isolation of blood group substances seemed to be specially 

 attractive. All these extracts are soluble — a particularly favourable 

 condition for the study of the chemical constitution of trans- 

 plantation antigens. Results of these experiments have been 

 pubHshed elsewhere (Albert and Lejeune-Ledant, 1959). Neither 

 crude gastric extracts prepared according to the technique of 

 Friedenreich and Hartmann (1938) nor more highly purified 

 extracts prepared with the phenol alcohol technique of Kabat 

 (1956), injected into recipients of another strain of mice, ever 

 produced a transplantation immunity. On the contrary, when 



