To identify strategies that enhance tumor-specific immunity in patients with ovarian carcinoma, 22 patients received four to six doses of i.p. recombinant IFN-γ (rIFN-γ), 200 μg/m² on days 1, 3, 5, 8, 10, and 12, and i.p. recombinant interleukin 2(rIL-2), either 6.0 × 10⁵ IU/m² (group A)or 1.0 × 10⁵ IU/m² (group B), on days 9,10, and 11. Two patients in group A also received T-cell lines expanded from peritoneal tumor-infiltrating lymphocytes (TILs) obtained after i.p. rIFN-γ/rIL-2 administration. Toxicity was manageable and included five nonhematological grade 3 or 4 events in 22 patients(23%). A patient had normalization of CA-125 values and a progression-free interval of 18 months, after receiving i.p. rIFN-γ/rIL-2 without TILs. Another patient who received i.p. rIFN-γ/rIL-2 plus TILs had stabilization of ascites and intra-abdominal tumors and >50% reduction in serum CA-125 values over 6 months. A third patient who received i.p. rIFN-γ/rIL-2 had stabilization of intra-abdominal tumors and ascites accompanied by CA-125 values of 50 to 100 units over 6 months. T-cell lines for adoptive immunotherapy were developed for only 3 of 20 patients who were treated with rIFN-γ/rIL-2. Large numbers of CD3⁻CD56⁺ adherent cells were expanded in rIL-2 in the remaining patients, precluding the development of T-cell lines. i.p. rIFN-γ, either alone or followed by rIL-2, increased proportions of human leukocyte antigen (HLA) class I⁺ and class II⁺ tumor cells and increased HLA class I staining intensity on peritoneal carcinoma cells. i.p. rIFN-γ plus rIL-2 also enhanced cytotoxic activity against Daudi and K562 cells and against allogeneic ovarian tumor cells. Increased cytotoxic activity was associated with an increase in the proportion of CD56⁺cells. IFN-γ and IL-2 transcripts were expressed more frequently after rIFN-γ and rIL-2 treatment. In addition, the proportions of CD45RA⁺ (naive lymphocytes) were increased, and CD8⁺DR⁺ lymphocytes were increased relative to CD8⁺CD69⁺ cells, which were decreased. IL-10 concentrations in peritoneal fluids were increased after treatment with rIFN-γ and the higher rIL-2 dosing (group A) but not in those treated with rIFN-γ and the lower rIL-2 dosing (group B). These results demonstrated that patients with ovarian carcinoma can tolerate treatment with rIFN-γ and rIL-2 and that rIFN-γ alone or rIFN-γcombined with rIL-2 enhances the expression of HLA class I and class II antigens on ovarian tumor cells, although immunosuppressive cytokines,such as transforming growth factor-β and IL-10, may persist. Treatment with rIFN-γ/rIL-2 i.p. did not facilitate the production of TIL-derived T-cell lines ex vivo.