XX XXXXXXX
Department of Genetics

February 9, 1959

Dr. BIIT Stone
Department of Genetics
University of Wéiseshsin
Madison, Wisconsin

Dear Bill:

This ts just a quick reply to your memorandum of Jan-
uary 21 to Nathan Smith. This seems to me as good a resumé
of the possibilities as could be set out. {tems | and 2 are
the ebvédus necesséties. | suppose the choice between them
depends on how easily one can set up tests for residual chimerism
for some of the other blood groups. Skin transplantation might
help to short-cut the other tests since ! think it Is a good

prediction that any chimera will be tolerant of donor skin. C,
item 5 is essentially the same as 2, substituting blood for ‘|
skin as the graft. in this case, it might be worth considering >

a test for tolerance of the grafted blood based not only on
the conventionalaagglutination reactions but also on the time
of survival of the RBC based on, for example, labeling with ~
radioactive Cr. =

Item 4 Is the only one that seems to me somewhat fuzzy,
since | don*t understand (1) any basis from which to expect
generalized tolerance and (2) you would be setting yourself a
difficult task in making a significant comparison.

Item 5 Is likely to be Impracticalsince the transfusions
would almost always Involve not merely ABO compatability but
most likely also Identity. In these cases, It Is dublous whether
there would be any effect and again you run Into problems of
accuracy of estimation.in the populations you will have at your
disposal.

Anyhow, one certainly hopes that you can get somewhere In
@ project of this kind although of course this will depend on large
measure on the kind of co-operation you actually get in the
medical school. 1! may possible take the opportunity of discussing
some similar projects when the new professor of pediatrics {s in-
stalled here. He happens to be someone | knew many years ago; his
name Is Normen Kretchmer.

We were happy to see youlhere, brief as your visit was, and
hope this will be repeated In future.

Yours as ever,

Joshua Lederberg