Phenotypic and functional characteristics of tumor-associated lymphocytes in patients with malignant ascites receiving intraperitoneal infusions of recombinant interleukin-2 (rIL-2)

In the course of a phase I trial, in which recombinant IL-2 (rIL-2) was infused intraperitoneally (i.p.) in patients with peritoneal carcinomatosis, we evaluated the effect on 'tumor-associated lymphocytes' (TAL) isolated from the ascitic fluid. No major changes in the percentages of cells expressing the CD3, CD4, CD8, Leu-7, OKMI, and WT-31 antigens were detected either in TAL or in peripheral blood lymphocytes (PBL) after 7 days of rIL-2 infusion. In contrast the percentages of TAL (but not PBL) expressing surface IL-2 receptor (Tac), or LAK-1 antigen were sharply increased. Analysis of cytolytic functions showed a potentiation of the lytic activity against natural-killer (NK) sensitive K562 target cells and the de novo appearance of lytic activity against fresh melanoma cells. In one patient IFN-γ was detected in the ascitic fluid following rIL-2 infusion. T-cell clones derived from the patient were analyzed for the IFN-γ production. While only approximately 40% of PB-derived control clones produced medium to low amounts of IFN-γ, all of the TAL-derived clones produced medium to high amounts of the lymphokine.