Improved remission induction rate with D-ZAPO but unimproved remission duration with addition of immunotherapy to chemotherapy in previously untreated children with ANLL

In 163 children with acute nonlymphocytic leukemia (ANLL), a D-ZAPO induction program consisting of daunomycin, 5-azacytidine, cytosine arabinoside, prednisone, and vincristine resulted in a remission rate of 71.8%. Immunologic therapy was employed during maintenance with the aim of prolonging remission and improving survival. The administration of immunotherapy consisting of a mixture of bacillus Calmette-Guérin (BCG) and allogenic acute myelomonocytic leukemic cells injected intradermally on day 14 of each of the first three monthly cycles of 6-thioguanine for ten days, 5-azacytidine and cytosine arabinoside for four days, and vincristine for one day did not improve remission duration or survival compared to that due to chemotherapy alone. Important prognostic factors identified in this study included a remission induction rate significantly better for females than males (P = 0.04), for children between the ages of 5 and 10 years compared to those greater than this age group (P = 0.01), and a prolonged remission duration (P = 0.04), and survival (P less than 0.01) for patients with initial white blood counts of less than 20 x 10(9)/liter.

Granulopoietic increase by BCG in mice

Repeated doses of the non-specific immunostimulant BCG were injected intraperitoneally, followed by serial measurement of serum colony stimulating factor (CSF), and CFU-C number and percent synthesizing DNA. Following primary challenge with BCG, CSF remained at low levels until day 7, rose to a peak by day 10, and remained elevated through 14 days. Secondary challenge resulted in a bi-phasic CSF response with a small peak on day 1 and a larger one by day 7. Following secondary challenge, the percent of CFU-C in 'S' phase doubled in 24 hours; CFU-C significantly increased in number by 48 hours. The studies suggest that the marrow toxicity of cycle active cytotoxic drugs might be altered by non-specific immunostimulants such as BCG.

Phase II study of the failure of vincristine and bleomycin for previously treated children with metastatic neuroblastoma: a report from the Childrens Cancer Study Group

Twenty-two patients with previously treated but progressive stage IV neuroblastoma received combination therapy with vincristine (1.0 mg/m2) followed in 6 hours by bleomycin (15 mg/m2). Therapy was administered twice weekly. No responses were seen in the 19 patients who received four or more doses of the bleomycin-vincristine combination.

Tumor-Growth Suppression in Vivo: Cooperation between Immune Lymphoid Cells Sensitized in Vitro and Nonimmune Bone Marrow Cells

Spleen cells from rats immunized with syngeneic (C58NT)D Gross virus-induced lymphoma cells restimulated in vitro with mitomycin C-treated (C58NT)D cells become cytotoxic to tumor targets and demonstrate an increased ability to adoptively confer antitumor immunity to nonimmune recipients. The purpose of the present studies was to determine whether nonimmune host cells participated in the local inhibition of tumor growth mediated by in vitro-activated cytotoxic cell populations. Adoptive transfer of antitumor immunity to irradiated syngeneic rats was more efficient when the recipients were reconstituted with normal bone marrow. A quantitative relationship was observed between the number of bone marrow cells administered and tumor-growth inhibition. Bone marrow cells from thymectomized, thoracic duct drained rats similarly were able to reconstitute lethally irradiated thymectomized recipients. Lymph node, thymus, or spleen cells were inactive when tested under the same conditions. Peritoneal-exudate (PE) cells contributed to decreased tumor growth in the presence or absence of sensitized lymphocytes. The results show that nonimmune bone marrow cells, although not required for tumor-growth suppression, interact synergistically with immune lymphocytes. These results suggest that in vitro-sensitized cells appear to inhibit tumor growth in vivo by at least two independent mechanisms: a direct, presumably cytotoxic effect on tumortarget cells and by indirect recruitment of a nonimmune radiosensitive bone marrow-derived host cell.

In vitro reactivity in allograft tolerance: persistence of mixed leukocyte culture reactivity in highly tolerant rats

Mixed leukocyte culture reactivity was studied in adult W/Fu rats judged to be highly tolerant after the inoculation of (W/Fu X BN)F1 hybrid spleen and bone marrow cells at birth. Reactivity was observed in a majority of tolerant donors tested and documented by quantitative dose-response and kinetic studies. Allograft tolerance cannot be explained by a complete lack of specific immune reactivity to tolerated alloantigens.

In Vitro Reactivity in Allograft Tolerance: Persistence of Mixed Leukocyte Culture Reactivity in Highly Tolerant Rats

Mixed leukocyte culture reactivity was studied in adult W/Fu rats judged to be highly tolerant after the inoculation of (W/Fu × BN)F1 hybrid spleen and bone marrow cells at birth. Reactivity was observed in a majority of tolerant donors tested and documented by quantitative dose-response and kinetic studies. Allograft tolerance cannot be explained by a complete lack of specific immune reactivity to tolerated alloantigens.

Relationship of Cellular Proliferation and the Generation of Cytotoxic Cells in an in Vitro Secondary Immune Response to Syngeneic Rat Lymphoma Cells

The role of cellular proliferation for the generation of cytotoxic activity in an in vitro secondary immune response to syngeneic lymphoma cells was investigated. Spleen cells from W/Fu rats immunized with the syngeneic (C58NT)D tumor proliferate and generate cytotoxic potential for tumor targets after exposure to mitomycin C-treated (C58NT)D cells in vitro. Elimination of proliferating cells by exposure to high specific activity 3H thymidine at appropriate intervals impaired the generation of cytotoxic activity. Elimination of cells proliferating to either syngeneic lymphoma or BN rat alloantigens allowed the remaining cells to generate cytotoxic potential to the second set of antigens. Elimination of proliferating cells also abrogated the ability of the in vitro generated cells to adoptively confer anti-tumor protection on nonimmune recipients. These results demonstrate that cellular division is required for the generation of cells which are cytotoxic in vitro and can adoptively confer anti-tumor protection in vivo.

Relationship of cellular proliferation and the generation of cytotoxic cells in an in vitro secondary immune response to syngeneic rat lymphoma cells

The role of cellular proliferation for the generation of cytotoxic activity in an in vitro secondary immune response to syngeneic lymphoma cells was investigated. Spleen cells from W/Fu rats immunized with the syngeneic (C58NT)D tumor proliferate and generate cytotoxic potential for tumor targets after exposure to mitomycin C-treated (C58NT)D cells in vitro. Elimination of proliferating cells by exposure to high specific activity 3H thymidine at approximate intervals impaired the generation of cytotoxic activity. Elimination of cells proliferating to either syngeneic lymphoma or BN rat alloantigens allowed the remaining cells to generate cytotoxic potential to the second set of antigens. Elimination of proliferating cells also abrogated the ability of the in vitro generated cells to adoptively confer anti-tumor protection on nonimmune recipients. These results demonstrate that cellular division is required for the generation of cells which are cytotoxic in vitro and can adoptively confer anti-tumor protection in vivo.

Passive Transfer of Systemic Tumor Immunity with Cells Generated in Vitro by a Secondary Immune Response to a Syngeneic Rat Gross Virus-Induced Lymphoma

Spleen cells taken from W/Fu rats 4 to 6 weeks after immunization with the syngeneic Gross virus-induced lymphoma, (C58NT)D cells, at a time when they lack detectable activity in a short-term 51Cr release assay, were previously shown to retain the capacity to generate cytotoxic activity upon reexposure to mitomycin C-treated lymphoma (C58NT)D cells in vitro. In the studies presented here, we evaluated whether in vitro sensitization of immune lymphoid cells before systemic transfer to a nonimmune recipient allows for more effective transfer of tumor immunity. The results show that the passive transfer of immune spleen cells after in vitro cocultivation with mitomycin-treated (C58NT)D cells allows for inhibition of growth of a subcutaneous inoculum of lymphoma cells. In contrast, spleen cells obtained 4 to 6 weeks after primary sensitization or after secondary in vivo sensitization did not effectively confer anti-tumor immunity. As few as 5 × 107 in vitro sensitized cells permitted complete inhibition of 106 (C58NT)D cells and also allowed for inhibition of the growth of 107 (C58NT)D-F cells, which was lethal to control animals. Immune cells sensitized with syngeneic thymocytes or normal spleen cells sensitized with (C58NT)D cells in vitro did not confer in vivo anti-tumor immunity. After systemic transfer of in vitro sensitized cells, delayed hypersensitivity occurred at the site of tumor inoculation and tumor growth was suppressed. Specificity of the passive immunity was shown by the failure to inhibit growth of a polyoma virus-induced sarcoma in rats which inhibited growth of the Gross virus-induced lymphoma cells. In vitro sensitized cells were more effective in the transfer of anti-tumor protection after 5 days, as compared to 2 days, of cocultivation with tumor. Results show that in vitro sensitized cells can effectively transfer systemic tumor immunity.

Passive transfer of systemic tumor immunity with cells generated in vitro by a secondary immune response to a syngeneic rat gross virus-induced lymphoma

Spleen cells taken from W/Fu rats 4 to 6 weeks after immunization with the syngeneic Gross virus-induced lymphoma, (C58NT)D cells, at a time when they lack detectable activity in a short-term 51Cr release assay, were previously shown to retain the capacity to generate cytotoxic activity upon reexposure to mitomycin C-treated lymphoma (C58NT)D cells in vitro. In the studies presented here, we evaluated whether in vitro sensitization of immune lymphoid cells before systemic transfer to a nonimmune recipient allows for more effective transfer of tumor immunity. The results show that the passive transfer of immune spleen cells after in vitro cocultivation with mitomycin-treated (C58NT)D cells allows for inhibition of growth of a subcutaneous inoculum of lymphoma cells. In contrast, spleen cells obtained 4 to 6 weeks after primary sensitization or after secondary in vivo sensitization did not effectively confer anti-tumor immunity. As few as 5 x 107 in vitro sensitized cells permitted complete inhibition of 106 (C58NT)D cells and also allowed for inhibition of the growth of 107 (C58NT)D-F cells, which was lethal to control animals. Immune cells sensitized with syngeneic thymocytes or normal spleen cells sensitized with (C58NT)D cells in vitro did not confer in vivo anti-tumor immunity. After systemic transfer of in vitro sensitized cells, delayed hypersensitivity occurred at the site of tumor inoculation and tumor growth was suppressed. Specificity of the passive immunity was shown by the failure to inhibit growth of a polyoma virus-induced sarcoma in rats which inhibited growth of the Gross virus-induced lymphoma cells. In vitro sensitized cells were more effective in the transfer of anti-tumor protection after 5 days, as compared to 2 days, of cocultivation with tumor. Results show that in vitro sensitized cells can effectively transfer systemic tumor immunity.

Generation of cytotoxic lymphocytes in vitro: response of immune rat spleen cells to a syngeneic gross virus-induced lymphoma in mixed lymphocyte-tumor culture

Spleen cells from W/Fu rats 4 to 6 weeks after immunization with syngeneic Gross virus-induced lymphoma (C58NT)D cells usually lack detectable activity in a short-term 51Cr release assay. The results presented here demonstrate that these spleen cells retain the capacity to generate significant proliferative and cytotoxic activity upon re-exposure to mitomycin C-treated (C58NT)D cells in vitro. Optimal conditions were defined in W/Fu rats for this secondary immune response in vitro to the (C58NT)D cells. The cytotoxic response was observed to be quantitative, reproducible, and specific. Optimal generation occurred 5 days after initiation of cultures with a 30:1 responding cell:stimulating cell ratio. In vitro generated cytotoxic cells inhibit tumor growth in vivo when administered as a mixture with tumor cells.

Generation of Cytotoxic Lymphocytes in Vitro: Response of Immune Rat Spleen Cells to a Syngeneic Gross Virus-Induced Lymphoma in Mixed Lymphocyte-Tumor Culture

Spleen cells from W/Fu rats 4 to 6 weeks after immunization with syngeneic Gross virus-induced lymphoma (C58NT)D cells usually lack detectable activity in a short-term 51Cr release assay. The results presented here demonstrate that these spleen cells retain the capacity to generate significant proliferative and cytotoxic activity upon re-exposure to mitomycin C-treated (C58NT)D cells in vitro. Optimal conditions were defined in W/Fu rats for this secondary immune response in vitro to the (C58NT)D cells. The cytotoxic response was observed to be quantitative, reproducible, and specific. Optimal generation occurred 5 days after initiation of cultures with a 30:1 responding cell:stimulating cell ratio. In vitro generated cytotoxic cells inhibit tumor growth in vivo when administered as a mixture with tumor cells.

Mixed leukocyte culture reactivity in operationally tolerant rats: Relationship of lymphocyte-mediated reactivity and serum-blocking activity

Tolerance to Brown Norway (BN) allografts was induced in Wistar Furth rats by neonatal inoculation of BN bone marrow cells or mixtures of (W/Fu x BN)F-1 hybrid spleen and bone marrow cells. Lymphoid cells from rats in which operational tolerance had been induced (maintenance of BN skin graft for more than 100 days) were studied for mixed leukocyte culture (MLC) reactivity. Peripheral blood lymphocytes from 10 of 25 W/Fu rats operationally tolerant to BN skin grafts showed MLC reactivity when exposed to BN antigens in vitro, implying that some degree of MLC reactivity is compatible with prolonged skin graft survival. These same rats also showed cytotoxic activity to BN fibroblasts in vitro regardless of their MLC status. MLC is quantitatively decreased and possibly qualitatively altered as compared to that of control W/Fu lymphocytes. The decrease was specific for the tolerated antigens. Serum from the tolerant rats inhibited cytotoxic but not normal MLC reactivity of W/Fu cells against BN antigens.

Allograft tolerance: presumptive evidence that serum factors from tolerant animals that block lymphocyte-mediated immunity in vitro are soluble antigen-antibody complexes

Serum factors present in rats rendered operationally tolerant to skin allografts by inoculation of allogeneic bone-marrow cells as newborns inhibit or "block" the cytotoxic effect of immune lymphocytes in vitro. These blocking factors were specifically removed from tolerant serum by absorption with allogeneic cells and later eluted from the absorbing cells in glycine buffer (pH 3.1). Blocking activity of the eluted material was resolved into fractions of low and higher molecular weight, which may be soluble histocompatibility antigen and specific alloantibody, respectively. Both antigen and antigen-antibody complexes may block in vitro, depending upon the assay used.

Tumor immunity: tumor suppression in vivo initiated by soluble products of specifically stimulated lymphocytes

Supernatant fluids of specifically stimulated lymphocyte cultures were purified. Fractions containing migration inhibition factor when injected intra-dermally into strain-2 guinea pigs produced a reaction similar in appearance to delayed cutaneous hypersensitivity. There was an accumulation of mononuclear cells at the injection sites and the growth of syngeneic tumor grafts at the sites was suppressed.