Reduced generation of suppressor cells in human mixed lymphocyte culture after radiotherapy

Suppressor T cells can be generated in mixed lymphocyte cultures (MLC) and their function is relatively resistant to irradiation in vitro. In this study the capacity to generate suppressor cells in MLC was determined before and after radiotherapy in 11 patients with endometrial cancer. After external pelvic radiotherapy with 40 Gy, the lymphocytes remaining in circulation demonstrated a lowered proliferation in MLC, and also the suppressive effect of MLC-activated cells was reduced. After radiotherapy, ten times as many MLC-activated cells were needed to get the same degree of suppression as before radiotherapy.