
2373. factors influencing the induction of enhancement and re-
sistance to methylcholanthrene-induced tumours in a syn-
geneic system
active immunological enhancement of the
growth of methylcholanthrene-induced tu-
mors was demonstrated in a syngeneic
system in mice.  enhancement was detected
3-5 wk. after preimmunization with
irradiated tumor suspension and was succeeded
after the 6th wk. by the development of
resistance to the tumor.  analysis by means
of adoptive and passive transfer showed
these to be true immunological phenomena.
enhancement and resistance were transferred
by serum and by the lymph node cells
of preimmunized mice.  threshold doses of
tumor cells were found to be the most
satisfactory for the detection of resistance
and enhancement in this system.
