376 IMMUNOGENETICS 



I would like to mention just one of the things we have been able to do with this 

 test. Earlier I had mentioned that thymic cells are not suitable for cytotoxic tests, 

 because the cells are not killed when one adds antibody and complement. Based on 

 some preliminary absorption tests, we had postulated that this was because there were 

 not enough antigen sites on the thymus cells and they were not fixing enough comple- 

 ment. Using the quantitative complement-fixation test, we have shown that this is 

 indeed the case; the thymic cells mixed with antibodies (even when the antibodies 

 were made against the thymic cells) fixed far less complement than preparations of cells 

 taken from either bone marrow, lymph nodes, or spleen. 



The cytotoxic technique and the complement fixation test may actually be 

 applied to peripheral blood, and if this could be done with humans, it could con- 

 ceivably open up the possibility, brought out by Dr. Russell, of typing human blood 

 for histocompatibility factors. 



Dr. Snell : Dr. Owen and Dr. Winn have given us a very adequate summary of 

 some of the methods of immunogenetics. There is little I could add. I am not an 

 immunologist, but I have acquired some knowledge secondhand from other people 

 working here. 



It has interested me to see, over the past ten to fifteen years, how the mouse has 

 finally come to be used as a tool in immunology. Twenty-five years ago about all one 

 could find in the literature were a few unsuccessful attempts to find blood groups in 

 mice. The results were always negative. Now the mouse is very much in business. 

 Of course one presumed the defect of the mouse originally was its small size. Here at 

 the Jackson Laboratory we circumvent that now by using large numbers of mice. 



I mention one additional technique to illustrate some of the tricks of the trade. 

 Dr. Owen mentioned absorption as a method of obtaining an antiserum with a single 

 specificity. That is a somewhat messy and time-consuming technique, and rather 

 particularly so in mice, in which the available amounts of serum and tissue are usually 

 small. Also the resulting antiserum may be heavily contaminated with tissue proteins. 

 A very simple and satisfactory alternative is absorption in vivo. One simply injects 

 the mice intraperitoneally with antiserum and then bleeds them perhaps an hour later; 

 the antibodies reactive with the recipient tissues are absorbed in vivo. The antiserum 

 may be diluted about one in ten, reducing the titer from about one in a thousand to 

 one in a hundred, but the antiserum is still usable for most purposes. 



Dr. Dray: Dr. Owen referred to some of the newer methods of immunochemistry 

 pertinent to mammalian genetics which I believe merit further emphasis. During the 

 past fifteen years, two very highly significant advances, agar-gel immunochemical 

 analysis and allotypy, have developed from the work of Dr. Jacques Oudin at the 

 Pasteur Institute. In 1946, Oudin discovered that when a mixture of antigens in 

 solution diffuses into a gel containing a mixture of precipitating antibodies, the multiple 

 bands of precipitate which result may be explained as due to the different antigen- 

 antibody systems present rather than to the Liesegang phenomenon as thought pre- 

 viously. 976 Through his work and others, agar-gel immunochemical analysis has 



