
2354. isoantigenic properties of tumors transgressing histocompatibility
barriers of the h-2 system
sublines capable of transgressing h-2 histocompatibility
barriers have been derived
from strictly strain-specific tumors by 1) passage
through newborn hosts of a
foreign genotype; 2) passage through adult h-2
incompatible recipients pretreated
with isoantisera directed against the tumor cells.
the nonspecific character induced
by these procedures was usually expressed in a
number of different h-2 incompa-
tible recipients.  the changes responsible for
the conversion to nonspecific growth
appeared to proceed in a stepwise fashion.
expression of the nonspecific character
required exposure to the foreign host environment
for more than 30 days.  at this
stage and during the subsequent 3 transfer
generations, reversion to strain-specific
growth occurred on back-transfer to the
strain of origin; after 4 passages in the
foreign hosts the nonspecific character was
permanently established, however, and
could not be reverted by prolonged passage
in the original host genotype.  the
growth rate of strain-specific tumors and
their nonspecific sublines was compared
in the strain of origin.  no difference was
found with one tumor, while the strain-
specific line grew better than the nonspecific
sublines with another.  this difference
was detected in the homozygous strain of
origin and in different semi-isologous f1
hybrids.  all lines grew better in the
homozygous strain than in the f1 hybrids,
however.  a comparison was made
between the concentration of h-2 isoantigenic
surface determinants in strain-specific
tumors and their nonspecific sublines by a
quantitative absorption technique in
vitro.  all nonspecific sublines had a lower
concentration of h-2 isoantigens than
the strain-specific tumors.  this suggests
that nonspecific tumors develop as a result
of immunoselection of variants resistant
to the homograft reaction and are characterized
by a lowered concentration of
h-2 antigens.
