The influence of estradiol and tamoxifen on the mixed lymphocyte reaction in rats.

The effect of estradiol and of the anti-estrogenic agent, tamoxifen, on mixed lymphocyte reactions was examined in the rat. Tamoxifen exerted a consistent inhibiting effect at concentrations ranging from 0.4-400 ng/ml. Estradiol was ineffective at physiological concentrations (0.4 ng/ml), whereas at pharmacological levels (400 ng/ml) significant inhibition was observed in some experiments but not in others. The inhibitory effect of both agents was more consistent in fetal calf serum containing medium when compared to that with autologous serum. Phenol Red had no effect on the outcome of these experiments.