Ovarian cancer-induced immunosuppression: relationship to tumor necrosis factor-alpha (TNF-alpha) release from...

Cytokines have been reported to be potential biological markers of, disease status in cancer patients. Tumor necrosis factor-alpha (TNF-alpha) is a key cytokine released from monocytes and macrophages. TNF-alpha is involved in essential biological functions such as immunoregulation, modulation of cell growth and differentiation. In this work, the role of TNF-alpha release in ovarian cancer patients was investigated. Fifty-five patients with ovarian cancer and 20 controls of matched age and parity were included in this study. TNF-alpha concentrations were measured in sera and cytosolic fractions of both groups. The results demonstrated a significant increase in TNF-alpha concentrations among patients compared to the control subjects (P < 0.001). Furthermore, a non-significant increase (P = 0.05, was observed between the different types (serous, Mucinous, and endometrioid) of epithelial ovarian cancers. Also TNF-alpha concentrations did not correlate with the disease stage. Moreover, immunohistochemical analysis of tissue specimens stained for TNF-alpha was positive in malignant lesions and negative for the normal ovarian tissue. These findings confirmed the TNF-alpha kinetics obtained by ELISA assays. Interestingly, TNF-alpha levels were also elevated in culture supernatants of PBMC stimulated by cytosolic fractions from malignant ovarian tissues. Blastogenic assays using cytosolic fractions from malignant ovarian specimens to stimulate healthy donor peripheral blood mononuclear cells (PBMC) showed a marked decrease in 3H-thymidine uptake compared to the cells stimulated by normal cytosols. To establish a cause-effect relationship between TNF-alpha release and inhibition of cell proliferation, the experiments showed that 3H-thymidine uptake by PBMC was markedly inhibited by recombinant human TNF-alpha (rh TNF-alpha) and that inhibition was significantly reversed when TNF-alpha monoclonal antibody was added to the cells. The data presented in this work indicate that TNF-alpha may play an important role in the biology of ovarian cancer and hence, tumor pathogenesis.