In vivo induction of the lymphokine-activated killer phenomenon: interleukin 2-dependent human non-major histocompatibility complex-restricted cytotoxicity generated in vivo during administration of human recombinant interleukin 2.

The availability of purified human recombinant interleukin 2 (IL-2) has enabled clinical trials to test its in vivo effects. We report here the immunological effects of 7 consecutive days of IL-2 treatment given to 25 patients with cancer in a clinical Phase I study. Peripheral blood lymphocytes obtained from patients following therapy with IL-2 had enhanced proliferative responses to IL-2 and enhanced direct cytotoxic activity on K562 target cells. This lytic activity was further augmented by the addition of IL-2 during the 51Cr release assay. Fresh peripheral blood lymphocytes from some patients who had just completed treatment at the higher IL-2 dose levels were able to kill both the natural killer-resistant Daudi cell line and fresh tumor cells while pretreatment samples and peripheral blood lymphocytes from healthy controls were not. This lytic activity was best detected when IL-2 was present in the in vitro effector assay. These results demonstrate that the administration of IL-2 to patients with cancer induces a population of effector cells able to directly destroy natural killer-resistant target cells, when assayed in the presence of IL-2.

Clinical adoptive chemoimmunotherapy with allogeneic alloactivated HLA-haploidentical lymphocytes: controlled induction of graft-versus-host-reactions.

A total of 13 cancer patients were treated with Adoptive Chemoimmunotherapy (ACIT) using alloactivated HLA haploidentical lymphocytes. Donor lymphocytes were activated in vitro using a pool of irradiated allogeneic lymphocytes (MLC-cells) and some further expanded by culturing in T-cell growth factor (TCGF-cells). The first 6 patients received i.v. cyclophosphamide (CPM) followed 24 h later by escalating doses of MLC-cells, then 7 days later they received an infusion of TCGF-cells. Minimal toxicity was seen. The next 7 patients received CPM (800 mg/m2) and a combined MLC and TCGF-cell infusion (total cell dose ranged from 0.79 x 10(10) to 2.26 x 10(10)). Of these 7 patients, 3 developed mild graft-versus-host reaction (GVHR) which resolved without treatment, and 2 patients had progressive GVHR which was arrested by methylprednisolone (2 mg/kg). Peripheral blood lymphocytes from these 2 patients, during the GVHR, had increased activated T-cells (OKT-10+ and OK-Ia+). In vitro expansion, in TCGF, of these activated T-cells enabled HLA typing to prove they were of donor origin. Only 1 clinical antitumor response was observed in the first 6 patients. The results of this study indicate that this form of ACIT can be given to patients with acceptable toxicity. Self-limited or easily controlled GVHR may be induced and primed donor cells persisting in the circulation are probably responsible. Further testing is required to determine whether the immune response induced by this form of ACIT may be therapeutically effective.

Destruction of autologous human lymphocytes by interleukin 2-activated cytotoxic cells.

Human and murine lymphocyte populations differentiate into lymphokine activated killer (LAK) cells after in vitro or in vivo exposure to interleukin 2 (IL 2). LAK cells mediate destruction of neoplastic tissue in vitro and have been reported to spare normal tissue. However, systemic toxicity is observed in mice and patients receiving IL 2 infusions. Some aspects of this toxicity are similar to that seen in graft-vs-host disease, suggesting that IL 2 may cause an immune-mediated destruction of normal tissues. We have evaluated this issue by examining the destructive potential of fresh human lymphocytes cultured in media containing highly purified recombinant human IL 2. In the absence of any exogenous antigen or allogeneic stimulating cells, strong proliferative responses were induced after 6 days of exposure to IL 2. Lymphocytes harvested from these 6-day cultures were highly cytotoxic to K562 and Daudi target cells. These IL 2-activated cells were also cytotoxic against autologous and allogeneic normal lymphocyte target cells. This autologous lymphocyte destruction was detected in media containing autologous serum and was directly dependent on the concentration of IL 2 added to the cultures. These studies demonstrate that populations of IL 2-activated lymphocytes, containing LAK activity, can mediate low-level but significant destruction of normal lymphocytes in vitro.

Clinical response of a patient with diffuse histiocytic lymphoma to adoptive chemoimmunotherapy using cyclophosphamide and alloactivated haploidentical lymphocytes. A case report and phase I trial.

Adoptive chemoimmunotherapy has cured experimentally induced tumors in animals, but its clinical use has been limited. Six patients were treated with refractory neoplasms in a Phase I study with cyclophosphamide (CPM) and alloactivated haploidentical lymphocytes. Patients received an immunosuppressive dose of CPM (800 mg/m2) followed by haploidentical lymphocytes primed in vitro with alloantigens in mixed lymphocyte culture (MLC). One week later patients received a second infusion of alloactivated lymphocytes expanded in T-cell growth factor (TCGF). The total number of cells given to each patient progressively increased, with a single patient receiving 35.5 X 10(9) cells. Transient febrile responses and delayed-type hypersensitivity reactions at the intravenous sites were the only toxicities noted. A complete clinical response lasting 12 weeks was seen in a single patient with diffuse histiocytic lymphoma. Our experience indicates that adoptive chemoimmunotherapy can be given to patients safely and merits further clinical testing.

The in vitro function of lymphocytes from 25 cancer patients receiving four to seven consecutive days of recombinant IL-2.

Twenty-five cancer patients received human recombinant interleukin-2 (IL-2) for 4 to 7 consecutive days in a Phase I trial. IL-2 was administered either as a daily intravenous bolus infusion (lasting 15 min), or as a continuous infusion lasting 24 h each day. Prior studies have demonstrated that in vivo administration of IL-2 at high doses is associated with changes in the phenotype of circulating peripheral blood lymphocytes (PBL) (determined with monoclonal antibodies), and the induction of augmented in vitro natural killer activity (NK) by PBL obtained following in vivo IL-2. We have noted that fresh lymphocytes obtained after 4-7 consecutive days of IL-2 (greater than or equal to 10(6) U/m2/day) show an augmented ability to kill NK-sensitive and -insensitive target cells (K562 and Daudi targets, respectively), especially when tested with IL-2 present during the 4-h 51Cr release assay. We have further analyzed lymphocytes in a battery of in vitro proliferative and cytotoxic assays. We present here the summary of this quantitative analysis of their responses in both antigen-specific and -nonspecific immune responses. Striking in vitro changes were observed in the proliferative response to IL-2 and in cytotoxicity stimulated by (or requiring) in vitro IL-2. Proliferative responses to antigens and to mitogens were not as dramatically altered following in vivo IL-2, nor were allospecific or allo-activated cytotoxic interactions. These studies indicate that the most striking changes in lymphocyte function measured in vitro following in vivo IL-2 are seen in those functions requiring IL-2.