Proliferation of CD4+CD25high+Foxp3+ regulatory T lymphocytes in ex vivo expanded ascitic fluid from primary and recurrent ovarian carcinoma

Objective

Regulatory T lymphocytes evoke the immune tolerance by suppressing and inactivating cytotoxic T lymphocytes. The objective of this study was to compare the proportion of regulatory T lymphocytes, precisely defined as CD4⁺CD25^high+Foxp3⁺ T lymphocytes, in primary and recurrent ovarian carcinoma before and after ex vivo expansion of ascites with interleukin-2 (IL-2).

Methods

Ascitic fluid samples were obtained from 26 patients with ovarian carcinoma. Lymphocytes were isolated from ascites and cell markers were analyzed by flow cytometry using anti-CD3/CD4/CD8/CD16/CD56/CD25 and anti-Foxp3 antibodies. Lymphocytes were incubated for 2 to 3 weeks and expanded ex vivo by IL-2 stimulation and their phenotypes were analyzed by flow cytometry.

Results

Following ex vivo expansion, ascitic fluid lymphocytes increased by a greater extent in the recurrent group than in the primary group. The proportion of ex vivo-expanded lymphocytes changed as follows; CD4⁺ T lymphocytes increased, CD8⁺ T lymphocytes decreased, and the proportion of CD3^-CD16⁺56⁺ NK cells was unchanged. The proportion of CD4⁺CD25^high+Foxp3⁺ regulatory T lymphocytes in CD4⁺ T lymphocytes increased after ex vivo expansion in both groups, but to a greater degree in the recurrent group.

Conclusion

This study showed that regulatory T lymphocytes, neither cytotoxic T lymphocytes nor NK cells, were extensively increased after ex vivo expansion, especially in recurrent ovarian carcinoma. These results may provide information that helps to guide the future development of adoptive immunotherapy against ovarian carcinoma.