Influence of adjuvant tamoxifen on blood lymphocytes

The blood lymphocyte population was studied in 23 breast cancer patients treated with adjuvant tamoxifen for 1.5-2 years, and in an equal number of control patients. The size and cellular composition of the blood lymphocyte population, as assessed by monoclonal antibodies directed against various subsets, did not differ between the two patient groups. However, lymphocytes from the tamoxifen-treated patients exhibited a significantly lower NK activity against K562 cells. In contrast, the proliferative response of lymphocytes to ConA was significantly higher. These results indicate that tamoxifen may modulate the immune system.