Search

Objective: In women with advanced ovarian cancer, levels of CD3-zeta on peripheral blood lymphocytes have previously been demonstrated to correlate with responsiveness to interleukin (IL)-2 therapy. The aims of this study were to identify the circulating component that modulated zeta expression and to define whether this suppressive activity could serve as a marker of biotherapy responsiveness., Methods: Sera were obtained from 17 patients with advanced ovarian cancer treated with intraperitoneal IL-2 in a phase I trial between 1987 and 1990. Nine of these patients exhibited a clinical response, while eight did not respond. Six additional sera from age-matched, noncancer-bearing women were used as controls. Jurkat E6-1 cells were used to assay modulation of CD3-zeta by sera and serum-derived components. Jurkat cells were exposed to serum or chromatographically fractionated serum components for 4 days and zeta expression was analyzed by Western immunoblots and quantitated by densitometry., Results: The effect of sera on zeta expression was compared between responders and nonresponders. Incubation of Jurkat cells with sera from responders suppressed CD3-zeta expression by 36.7% (vs. control treated), while treatment with sera from nonresponders produced an 83.7% reduction in zeta expression (difference between groups, P < 0.001). When sera from nonresponders were chromatographically fractionated, a <20 kDa component was identified that correlated with decreased zeta chain expression. This component was diminished in the sera of responders and absence in controls., Conclusions: Thus, in patients with advanced ovarian cancer, a circulating component, which decreases zeta expression, can be identified as a marker for responsiveness to IL-2 therapy.

Purpose: The accumulation of shed plasma membrane vesicles in the peripheral circulation is unique to cancer. Because these membrane fragments (MFs) express biologically active components, such as Fas ligand (FasL), the objective of this study was to define the link between the presence of shed membrane vesicles, apoptosis, and suppression of T-cell receptor/CD3-zeta expression in T lymphocytes of patients with ovarian cancer., Experimental Design: MF shedding was measured chromatographically in sera from women with ovarian cancer (n = 11) and, as controls, non-cancer-bearing females (n = 9) and women with benign ovarian disease (n = 4). FasL associated with these shed fragments was assayed by Western immunoblots, whereas HLA class I expression was defined by slot-blotting. The effect of shed MFs on CD3-zeta expression was evaluated using a T-cell bioassay, and apoptosis of circulating T cells was measured by a cell-death ELISA and electrophoretic analysis of caspase-3., Results: MFs were undetectable in control sera, and their levels were significantly elevated in sera from women with ovarian cancer. These tumor-derived MFs expressed 41-kDa FasL and HLA class I antigens. In co-incubation experiments, dose-dependent suppression of T-cell receptor/CD3-zeta expression by MFs was observed. Decreases in zeta expression correlated with the level of FasL in MFs but not with the level of HLA. The suppression of CD3-zeta by MFs appeared to be linked to the induction of apoptosis and caspase-3 within T cells., Conclusion: Our results suggest that FasL associated with tumor-derived MFs is responsible for apoptosis of T lymphocytes and a concomitant loss of zeta-chain expression in patients with ovarian carcinoma.