Immunosuppressive activity of lymphocyte mitogenesis by breast cancer-associated p43.

Placental isoferritin (PLF), an acidic isoform of ferritin, and its unique superheavy chain of 43 kDa (p43) has been described to be synthesized by human breast cancer cells. Physiologically, p43 PLF produced by the placenta is involved in immune suppression of maternal lymphocytes aimed at fetal antigens. A study was carried out to elucidate a paradigm of p43 occurrence in breast cancer patients. Immunosuppression of cytotoxic CD8+ lymphocytes was measured via inhibition of blast transformation in concanavalin A (ConA) stimulated peripheral blood lymphocytes (PBL) using 3H-thymidine uptake in vitro. PBLs were cultivated from 29 women having benign lesions in the breast as well as from 41 patients with breast adenocarcinoma. In breast cancer patients addition of p43 significantly inhibited the activation of lymphocytes proliferation by ConA compared to women with benign tumors. The addition of indomethacin or levamisole did not influence this inhibitory effect of p43 in breast cancer patients. Presence of interleukin-2 in cultures was able to overcome the inhibitory effect of p43 on CD8+ lymphocytes proliferation from women having breast adenocarcinomas and to increase its value in patients with benign lesions.