Introduction/Background Th9 lymphocytes is a recently researched subpopulation of lymphocytes that are, supposedly, involved in antiparasitic activity. Growing amount of data suggests their important role in various types of neoplasms. So far, their role in ovarian cancer has not been thoroughly investigated. This presentation is intended to publish preliminary results of a research currently being conducted by the authors.

Methodology So far, 12 patients with ovarian malignancies and 5 control group patients have been subjected to this study. Samples of peripheral blood and peritoneal fluid of subjects have been collected and analyzed with use of flow cytometry in terms of Th9 (triple positive: CD3+, CD4+, Il-9+) lymphocyte percentage before and after stimulation. Results of assays were compared with clinical data obtained from the patients and their medical records.

Results Patients with ovarian cancer have significantly higher Th9 lymphocyte percentage in peritoneal fluid after stimulation in comparison with control group (1,34% vs 0,43%; p-value=0.03). There is an insignificant statistical corelation between ROMA value and Th9 lymphocyte percentage in peripheral blood and ascitic fluid. The corelation between Th9 lymphocyte percentage in peripheral blood after stimulation and malignant disease has not been detected.

Likewise, CD4+/CD8+ proportion in peripheral blood is higher in ovarian cancer patients compared with clinically known laboratory ranges.

Conclusion Th9 lymphocytes are present in ascitic fluid of ovarian cancer patients and exhibit higher mitotic activity after stimulation. Immunological imbalances in cytotoxic and humoral response is one of possible pathogenetic mechanisms involved in progress of the disease. Further study is needed in order to understand the exact mechanism of action as well as prognostic value of Th9 lymphocytes in ovarian cancer.

Disclosures The authors hereby disclose no conflict of interests.