METHODS IN MAMMALIAN IMMUNOGENETICS 379 



Dr. Cohen: I have tried the techniques of Masouredis 857 in studying gene- 

 dosage effects on rabbit red-cell antigen and had no success. There appeared to be 

 too much nonspecific absorption of the tagged antibody so that the small differences 

 were difficult to distinguish. I used, as in my test system, tagged antibody which had 

 been absorbed on the specific cell and then eluted. The tagged eluate was then used 

 on cells of known genotypes. Masouredis did it this way in his human work and was 

 successful. It did not work in the rabbit red-cell system. 



Dr. Reed: Fluorescent antibodies are, of course, the other major type of labeled 

 antibody. Also, several tritium-labeled antibodies have been prepared to date. 1037 - 

 1045 Tritium-labeling is easily done by the Wilzbach method, 1274 by sending the 

 lyophilized antiserum to one of several firms to be exposed to tritium gas. 



Dr. Cohen: The fluorescent antibody technique has been used for the identifica- 

 tion of blood-group antigens by Cohen and her co-workers 209 as a means of investigating 

 problems in immunologic genetics and hematology. They used human anti-^4, anti-5, 

 anti-Z), and anti-C to identify minor cell populations occurring in a mother which 

 might be derived from the transplacental transfer of cells from the fetus to the mother. 

 This technique could also detect minor cell populations arising through mutations or 

 through induction of chimeras. 



Dr. Gowen: It has not been mentioned, but there are real possibilities for isolating 

 animal strains that will be good producers of immune serum. In my own experience 

 there are great differences in serum titers in random-bred animals, indicating dif- 

 ferences in their genetic capacity to make immune antibodies. The isolation of strains 

 with high production of immune sera could be of both practical importance and 

 contributory to better understanding of immune phenomena. 



Dr. Barrett: It has been said by several, on what I believe to be uncontrolled 

 observations of race III rabbits produced by Dr. Sawin, that they are better- than- 

 average antibody producers. I have used some of these rabbits myself. I would not 

 say whether they are better or not; they certainly are quite good. 



Dr. Dray: Dr. Barrett raises an interesting problem concerning the individual 

 variation of rabbits in their capacity to produce antibodies. Gamma-globulin groups 

 of rabbits may offer an approach to this problem, since at least 36 genotypes based on 

 three alleles at two loci are now known. 290 Since antibodies are found among the y- 

 globulins, the possibility exists that the genetic control of y-globulin allotypes may be 

 correlated with the genetic control of the capacity to produce antibodies. Such a 

 result would also have interesting implications concerning theories of antibody 

 formation. 



