Therapy of leukemia by nonimmune syngeneic spleen cells

In previous studies mice bearing an established transplanted syngeneic leukemia were cured by the adoptive transfer of immune lymphoid cells inoculated as an adjunct to chemotherapy, whereas nonimmune cells had no effect. By employing a smaller initial tumor inoculum to enhance the sensitivity of the chemoimmunotherapy model, the current study demonstrated that cells from normal nonimmune donors can also eradicate tumor. Thus, adult BALB/c mice given a lethal dose (1 x 10(4)) of LSTRA on day 0 were treated on day 5 with cyclophosphamide (CY) alone or CY plus nonimmune cells. Untreated mice all died by day 10. Cy alone prolonged median survival time (MST) to day 20, but all mice died. Treatment with CY plus 1 x 10(7) nonimmune cells prolonged the MST to day 26 and cured 16 of 48 mice. The effector cells, present in the spleens of normal and nude mice, were nonadherent lymphocytes resistant to anti Thy + C. These results are consistent with this effector cell in adoptive chemoimmunotherapy being an NK cell. However, they are distinct from classical NK cells since they are not directly cytotoxic in vitro in a short term CRA and do not neutralize tumor in vivo in a Winn assay.

Therapy of leukemia by nonimmune syngeneic spleen cells

In previous studies mice bearing an established transplanted syngeneic leukemia were cured by the adoptive transfer of immune lymphoid cells inoculated as an adjunct to chemotherapy, whereas nonimmune cells had no effect. By employing a smaller initial tumor inoculum to enhance the sensitivity of the chemoimmunotherapy model, the current study demonstrated that cells from normal nonimmune donors can also eradicate tumor. Thus, adult BALB/c mice given a lethal dose (1 x 10(4)) of LSTRA on day 0 were treated on day 5 with cyclophosphamide (CY) alone or CY plus nonimmune cells. Untreated mice all died by day 10. Cy alone prolonged median survival time (MST) to day 20, but all mice died. Treatment with CY plus 1 x 10(7) nonimmune cells prolonged the MST to day 26 and cured 16 of 48 mice. The effector cells, present in the spleens of normal and nude mice, were nonadherent lymphocytes resistant to anti Thy + C. These results are consistent with this effector cell in adoptive chemoimmunotherapy being an NK cell. However, they are distinct from classical NK cells since they are not directly cytotoxic in vitro in a short term CRA and do not neutralize tumor in vivo in a Winn assay.

Disappearance of Ph1-positive cells in four patients with chronic granulocytic leukemia after chemotherapy, irradiation and marrow transplantation from an identical twin

Four patients (21, 41, 13 and 38 years of age) with a history of chronic granulocytic leukemia for 12, 10, 11, and 106 months, respectively, were treated with dimethyl busulfan, cyclophosphamide, 920 rads of total-body irradiation and intravenous marrow infusion from normal, genetically identical twins. Serial chromosome analyses were performed on marrow aspirates cultured without mitotic stimulants. No Ph1-positive cells were detected in the marrows from the normal twins, whereas just before therapy, all 100 metaphases examined from each patient were Ph1-positive. Chromosome analyses were performed three to five times per patient after transplantation, and not a single Ph1-positive cell was detected. The patients remain hematologically normal 22, 23, 26 and 31 months after transplantation. The results show that the Ph1-positive clone can be eradicated by vigorous therapy and that the marrow in chronic granulocytic leukemia can be repopulated by stem cells from normal twins.

Tumor Neutralization, Immunotherapy, and Chemoimmunotherapy of a Friend Leukemia with Cells Secondarily Sensitized in Vitro:

The aim of this study was to determine if cells primed in vivo could be rendered more effective in killing tumor by secondary sensitization in vitro. C57BL/6 mice were primed with a viable antigenic syngeneic Friend leukemia (FBL-3). The immune spleen cells secondarily sensitized by 5-day culture with irradiated FBL-3 (CiFx) became significantly more effective than fresh noncultured immune cells (Ci) in in vitro cytotoxicity, tumor neutralization (Winn assay), and immunotherapy of an early leukemia. However, in chemoimmunotherapy of advanced leukemia, CiFx were no more effective than Ci. Moreover, Ci cultured with irradiated C57BL/6 spleen cells (CiCx), i.e., without secondary sensitization in vitro, became markedly less effective than noncultured Ci. C57BL/6 mice inoculated with 5 × 106 FBL-3 on day 0 received on day 5 cyclophosphamide (CY) plus Ci, CiFx, or CiCx. CY alone doubled the median survival time (MST) to day 26. As an adjunct to CY, Ci or CiFx prolonged the MST to day 53 and day 55 and cured 16/72 and 20/66 mice, respectively, whereas CiCx prolonged the MST to only day 33 and cured 1/36 mice. To determine if the lack of enhanced effect after secondary sensitization in vitro reflects the nature of primary exposure to antigen, other priming regimens were studied. When mice were primed with irradiated FBL-3 or with cross-reacting MSV, CiFx were more effective than Ci in chemoimmunotherapy. Thus, enhancement by secondary in vitro sensitization of primed cells to eradicate advanced leukemia is dependent upon the method of priming and cannot be predicted by results of the in vitro tumor cytotoxicity, tumor neutralization, or immunotherapy of early leukemia. Moreover, primed cells lose effectiveness in tumor therapy if cultured without secondary stimulation.

Tumor Neutralization, Immunotherapy, and Chemoimmunotherapy of a Friend Leukemia with Cells Secondarily Sensitized in vitro

The aim of our study was to induce in vitro a secondary response to a C57BL/6 Friend leukemia (FBL-3) by C57BL/6 lymphoid cells, to document their enhanced anti-tumor cytotoxicity in vitro and to study their anti-tumor effect in vivo by tumor neutralization (Winn assay) and tumor therapy of progressive FBL-3 in C57BL/6 mice. Spleen cells (Ci) from mice immunized once in vivo with FBL-3 were cultured for 5 days with either x-irradiated FBL-3 (CiFx), C57BL/6 spleen cells (CiCx), BALB/c spleen cells (CiBx) or without any x-irradiated cells (Ci-cult.) and their activity subsequently was assayed in vitro and in vivo. CiFx cells were markedly more cytotoxic in vitro by the 51Cr release assay than were CiCx or CiBx and were most effective in tumor neutralization (Winn assay). For adoptive immunotherapy, mice given lethal (104) FBL-3 i.p. on day 0 received the cultured spleen cells on day 1. Treatment with 5 × 106 CiFx cured 14 of 14 mice whereas 19 of 20 mice given 5 × 106 CiCx or CiBx died with tumor. For adoptive chemoimmunotherapy of advanced leukemia, mice were given 107 FBL-3 i.p. on day 0. On day 5, they received cyclophosphamide (CY) plus cultured spleen cells. Untreated mice died by day 14. CY alone prolonged survival but all mice died within 4 weeks. Treatment with CY plus 5 × 106 Ci-cult. or CiBx was no more effective than CY alone—40 of 40 mice died with tumor. However, CY plus 5 × 106 CiFx cured 16 of 22 mice. Thus, cells generated in a secondary response in vitro were not only cytotoxic in vitro and effective in tumor neutralization, but were also curative in immunotherapy of an early leukemia and in chemoimmunotherapy of an advanced leukemia.

Reduction of fatal graft-versus-host disease by 3H-thymidine suicide of donor cells cultured with host cells

The effect of the tritiated thymidine (3H-TdR) suicide technique on the ability of donor cells to induce fatal graft-versus-host disease (GVHD) was studied. C57BL/6 (H-2b) spleen cells were stimulated in vitro with irradiated BALB/c (H-2d) Moloney lymphoma cells in mixed culture and 3H-TdR of high-specific activity added to eliminate proliferating cells. The ability of such cells to induce fatal GVHD was assayed by injecting them i.v. into adult BALB/c mice immunosuppressed with cyclophosphamide (180 mg/kg). These cells induced fatal GVHD in fewer mice (52 per cent) than did C57BL/6 cells cultures with BALB/C lymphoma cells but without 3H-TdR (87%) and C57BL/L cells cultured with irradiated C57BL/6 cells with (95 per cent) or without 3H-TdR (86 per cent). Thus, the 3H-TdR suicide technique greatly diminished the ability of cells to induce lethal GVHD.

Induction of increased graft-versus-host disease by mouse spleen cells sensitized in vitro to allogeneic tumor

The aim of our study was to sensitize cells in vitro, follow their proliferative and cytotoxic responses, and determine their ability to cause lethal graft-versus-host disease (GVHD). C57BL/6 (H2b) spleen cells were incubated with irradiated BALB/C (H2d) Moloney lymphoma cells (LSTRA) in mixed leukocyte culture conditions for 2, 4, or 6 days and then tested. The maximal proliferative response occurred after 4 days. In vitro cytotoxic reactivity against 51Cr-labeled LSTRA was generated by 4 days (76.3+/-3.1% 51Cr released) and 6 days (133.0+/-4.8%) of sensitization but not by 2 days (-0.2+/-1.1%). Induction of fatal GVHD was assayed by injecting graded doses of the C57BL/6 spleen cells i.v. into adult BALB/c mice pretreated with cyclophosphamide, 180 mg/kg. Cells sensitized for 2 days were effective but no more so than were (control) cells cultured with irradiated C57BL/6 spleen cells. However, cells sensitized longer were far more active than the control cells. Cells sensitized for 4 days killed 70 of 88 mice (80%), and those sensitized for 6 days killed 37 of 48 mice (77%), whereas control cells killed only 42 of 90 mice (47%) (P less than 0.005). Thus, cells sensitized in vitro exhibited an increased ability to induce GVHD in vivo, which was temporally associated with the development of cytotoxicity in vitro.

Use of dimethylmyleran in adoptive chemoimmunotherapy of two murine leukemias

Dimethylmyleran (DMM) is an antitumor agent that has minimal effects on immunity. In a study of its usefulness in adoptive chemoimmunotherapy, C57BL/6 mice inoculated on day 0 with C57BL/6 Friend virus-induced leukemia (FBL-3) were treated on day 5 with 12 mg DMM/kg [less than LD10 (lethal dose for 10% of mice)] plus C5BL/6 spleen cells. All untreated mice died, with a median survival time (MST) of 17 days. DMM alone or with nonimmune cells prolonged survival to day 20, and 3/53 mice survived beyond day 60. By contrast, 12/25 mice treated with DMM plus cells immune to FBL-3 were cured. Similar results were obtained in C57BL/6 mice with syngeneic Rauscher virus-induced leukemia (RBL-5). Untreated mice died, with an MST of 14 days. DMM alone or with nonimmune cells prolonged the MST to 21 and 26 days, respectively, and 3/26 and 6/28 mice were long-term survivors. However, 13/28 mice were cured by DMM plus cells immune to antigenically related FBL-3. Lethal irradiation of cells immune to FBL-3 abolished their efficacy. Finally, in contrast to the efficacy of sublethal DMM plus immune cells, an LD100 of DMM (20 mg/kg) plus hematopoietic reconstitution with nonimmune syngeneic cells was not effective against FBL-3 OR RBL-5. The results emphasized the critical role of immune cells in chemoimmunotherapy even when the drug used is nonimmunosuppressive.

Combination chemotherapy for acute nonlymphoblastic leukemia in adults

Between January 1973 and February 1975, 77 adults with acute nonlymphoblastic leukemia were treated with a combination of daunorubicin, cytosine arabinoside, 6-thioguanine, prednisone, and vincristine in university-affiliated and private institutions. After 31 patients were treated (regimen 1) the doses of all drugs were significantly increased (regimen 2). Regimes 1 and 2 yielded CR rates of 59% (17 of 29 patients) and 70% (32 of 46 patients) respectively. With regimens 2 the mean number of courses and the median number of days to CR decreased from 3 to 1.4 and from 46 to 29 respectively. Failure to achieve CR was due to persistent leukemia during regimen 1 and fatal infections during regimen 2. With regimen 2 ten of 20 patients (50%) greater than 50 years had CR compared to 22 of 26 patients (85%) less than 50 years. CR rates were similar in community and university institutions.