Fisiopatologia. — Membrane vesicles, shed from in vitro cultured human breast carcinomas cells, inhibit lymphocytes proliferation.

Membrane vesicles are released by the cells of the two human breast carcinoma cell lines 8701-BC and MCF-7. Vesicles express on their surface HLA Class I molecules and tumor associated antigens and they appear to have a strong, dose dependent, inhibitory effect on thymidine incorporation by periferal lymphocytes. Inhibition is evident on both PhA stimulated or non stimulated lymphocytes. The inhibitory effect is visible after three days of culture. Vesicle addition does not cause cytotoxic effects since inhibited lymphocytes are still capable to exclude Trypan blue. No apoptoptic cells were observed.