NATURAL-KILLER (NK) CELL-ACTIVITY OF WOMEN WITH GROSS CYSTIC-DISEASE IS INHIBITED IN-VITRO BY BREAST CYST FLUID

Gross cystic disease (GCD) represents an advanced form of fibrocystic disease of the breast. Bearers of macrocysts have been reported to be at risk of developing breast cancer. Natural killer (NK) cells are a l ymphocyte subset deeply involved in immunosurveillance against neoplas ia. We investigated whether breast cyst fluid (BCF) aspirated from pat ients with GCD could affect in vitro the spontaneous and lymphokine-in ducible NK activity of peripheral blood mononuclear (PBM) cells concom itantly drawn from the same patients. PBM cells exposed to BCF were ev aluated by a standard cytotoxic assay, using K562 cells as a target, i n the presence or absence of lymphokines. In vitro incubation of PBM c ells with BCF resulted in a consistent decrease of NX cell activity (m ean level of suppression about 50%; p<0.001). Furthermore, exposure of PBM cells to BCF completely prevented the IFN-gamma-dependent enhance ment and consistently reduced the IL-2-induced NK activity (p<0.01). T he phenomenon was more apparent for type II cyst BCF. Our data are com patible with an immunosuppressive effect of BCF, potentially leading t o altered <<local immunosurveillance>>.