Incorporation of ¹²⁵I-iododeoxyuridine into target cells as an assay for cell immunity

We assayed cell immunity by measuring the decrease of ¹²⁵I-iododeoxyuridine (¹²⁵IUDR) uptake into target cells when incubated with sensitized effector cells. This method was suitable for target cells in monolayer or in suspension cultures. A labeling regimen was used in which ¹²⁵IUDR was added after a short exposure of the target cells to effector cells. This obviated the need to preplate the target cells in the culture vessel a day before or to prelabel them. Thereby, the test was further simplified and shortened. This method was used successfully in allogeneic and syngeneic (tumor-specific) systems. In the syngeneic systems, lymph node cells (LNC) from mice with a syngeneic 3-methylcholanthrene-induced tumor inhibited ¹²⁵IUDR incorporation into the corresponding tumor cells. LNC from mice with a different syngeneic 3-methylcholanthrene-induced tumor did not inhibit ¹²⁵IUDR incorporation into the first tumor cells.