TUMORICIDAL CYTOKINES ENHANCE RADIOIODINE UPTAKE IN CULTURED THYROID-CANCER CELLS

We explored whether the stimulation of iodine uptake by interferons se en in a rat thyroid cell line is reproducible in human thyroid cancer and thus applicable to enhance the efficacy of radioiodine therapy. Me thods: Surgical specimens from 12 papillary and 2 follicular adenocarc inomas were minced and seeded in culture trays. After 14-16 days in a medium supplemented with 5% calf serum, we measured cellular uptake of I-125 during a 40-min incubation period. Results: In 8 of 12 papillar y and all 2 follicular carcinomas, interferon-gamma significantly stim ulated iodine incorporation. The four nonresponder tumors had lower ba sal iodine uptake and relatively less differentiation of histologic fe atures. The effect was dose dependent (0-100 U/ml), and the average ma ximum increase in responding cases was 35.1% over basal values. Tumor necrosis factor-alpha alone did not alter uptake, but at 300 U/ml it f urther enhanced the effect of interferon-gamma in the two follicular t umors. In addition to the pure cytokines, supernatant from lymphocyte culture conditioned with a bacterial immunostimulator also boosted rad ioiodine trapping in thyroid cancer cells. Conclusion: These in vitro results warrant animal experiments to test potential usefulness of tum oricidal cytokines in radioiodine therapy.