The heart is more susceptible to rejection than the kidney but still less susceptible than skin
allografts. ifl, 15-17 Barker and Billingham” provided a striking example of this in 1971 when
they compared the fate ofskin and hearts transplanted from F344 by Lew backcross olIspring
to Lew recipients. There was only a small difference in the survival of skin and hearts with
parent-to-parent strain allografts. However, with the backcross grafts, in which the number of
histocompatibility (H) differences were reduced by independent assortment, 21 of 22 skin …