Viable splenocytes
were isolated from various animal treatment groups at different
time points after primary hepatic tumor inoculation. In
vitro stimulation was performed for 5 days in 24-well plates,
each well containing 6 x 106 splenocytes, recombinant mIL-2
(20 units/ml) and 5 x 105 MCA-26 cells that had received
15,000 rad (150 Gy) of radiation. Effector cells were coincubated
with Cr51 (150 ,uCi for 5 x 106) labeled target cells
for 4 hr at 37°C in different effector and target cell ratios.
Parental MCA-26 cells were used as target cells for the CTL
assay. After incubation, the radioactivity of 100 ,lI of the
supernatant was counted in a gamma counter. The percentage
of specific cytolysis was calculated as (experimental release -
spontaneous release)/(maximum release - spontaneous release)
x 100.
Total radioactivity present in target cells was analyzed by
lysing the cells with 10% SDS. Data represent the mean of
triplicate cultures and were analyzed by logistic regression.