Mesna versus hyperhydration for the prevention of cyclophosphamide-induced hemorrhagic cystitis in bone marrow transplantation.

Hemorrhagic cystitis is a major complication of high-dose cyclophosphamide therapy used in preparation for allogeneic or autologous bone marrow transplantation. Although previous reports had suggested that the sulfhydryl-containing compound mesna might be superior to forced diuresis in preventing hemorrhagic cystitis, there were concerns about the effect of mesna on engraftment in these studies. To address these concerns, 100 patients were randomized to receive mesna or forced saline diuresis while undergoing bone marrow transplant conditioning with regimens that included high-dose cyclophosphamide. To try to minimize the likelihood of graft rejection, patients who were being transplanted with cyclophosphamide as a sole agent were excluded from the study. After randomization and administration of therapy, patients were monitored by microscopic and dip-stick urinalyses; they were also followed for effects of therapy on engraftment. The incidence of consistent or severe hematuria was 33% in the mesna arm and 20% in the hyperhydration arm (P = .31). Severe bleeding occurred in 12.5% of mesna patients and 7.5% of hyperhydration patients (P = .71). No unexpected toxicities were encountered, and engraftment times did not differ. Based on this randomized trial of 100 patients, we conclude that mesna and hyperhydration are equally effective in preventing cyclophosphamide-induced hemorrhagic cystitis in bone marrow transplantation patients.

Busulfan, cyclophosphamide, and melphalan conditioning for autologous bone marrow transplantation in hematologic malignancy.

Sixteen patients with poor-prognosis acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL), and non-Hodgkin's lymphoma (NHL) underwent conditioning with busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) (BUCY-2) plus melphalan (90 or 135 mg/m2) and autologous bone marrow transplantation (AuBMT) in a phase I study. At the melphalan dose of 90 mg/m2, grade greater than or equal to 3 regimen-related toxicity (RRT) was observed in five patients (31%; 95% confidence interval [CI], 11% to 59%), with hepatic (venoocclusive disease [VOD]) and urinary (hemorrhagic cystitis) RRT being the most frequent complications. Further escalation of the melphalan dose to 135 mg/m2 was deemed excessively toxic, as three of five patients had grade greater than or equal to 3 RRT. Following this experience, 21 patients with multiple myeloma (MM) and chronic myelogenous leukemia (CML) were treated with BUCY-2 plus melphalan 90 mg/m2 and AuBMT in separate studies. Three of these patients--all with extensively pretreated MM--had grade greater than or equal to 3 RRT (14%; 95% CI, 3% to 36%); no others had grade greater than or equal to 3 RRT. Therefore, a total of eight of the 37 patients (22%; 95% CI, 10% to 38%) who received BUCY-2 plus melphalan 90 mg/m2 conditioning developed grade greater than or equal to 3 RRT; three of these patients (8%; 95% CI, 3% to 25%) died of RRT. Although limited by the relatively small number of patients, our analysis of the patients receiving this regimen showed that the presence of parameters denoting the lymphoid diagnostic group (ie, ALL, NHL, and MM), more extensive pretreatment, and/or more advanced disease status were associated with a higher incidence of grade greater than or equal to 3 RRT. Response data on the AML, ALL, and NHL patients who received BUCY-2 plus melphalan 90 mg/m2 were analyzed: three patients (all with AML in first or second remission) are leukemia-free at 3.0, 2.8, and 1.4 years after AuBMT. The actuarial 2-year event-free survival in this group is 17% (95% CI, 5% to 54%). Response data on the MM and CML patients will be reported subsequently. BUCY-2 plus melphalan at a dose of 90 mg/m2 before AuBMT produces acceptable toxicity in patients who are not heavily pretreated. A full evaluation of the antineoplastic effects of this regimen requires further study.

Regimen-related toxicity of a busulfan-cyclophosphamide conditioning regimen in 70 patients undergoing allogeneic bone marrow transplantation.

The regimen-related toxicity (RRT) of a busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) conditioning regimen (BuCy) was evaluated in 70 consecutive patients undergoing allogeneic bone marrow transplantation for hematologic malignancies. Patients were given toxicity gradings retrospectively in each of eight organ systems (cardiac, bladder, renal, pulmonary, hepatic, CNS, stomatic, and gastrointestinal) according to a recently developed RRT scale. A set of patient, disease, and treatment parameters (age, sex, diagnosis, Eastern Cooperative Oncology Group [ECOG] score, preconditioning liver function tests [LFT], prior chemotherapy exposure, disease status, graft-versus-host disease [GVHD] prophylaxis, antimicrobial agent use, hematologic recovery, and severity of acute GVHD) was statistically analyzed to determine significant predictors of RRT. The most common significant organ toxicities were stomatic (87% of patients; 63% grades II to IV) and hepatic (83% of patients; 44% grades II to IV). Renal and gastrointestinal toxicities were not uncommon (35% and 27%, respectively) but were rarely serious (9% and 1% grades II to IV, respectively). Twelve patients developed grade III toxicities of the following systems: hepatic (seven), pulmonary (two), bladder (two), and CNS (one). Females had more frequent stomatitis (P = .04) and hepatic RRT (P = .004). Patients receiving methotrexate in their GVHD prophylactic regimen experienced more grade II to IV stomatitis (P = .04) and hepatic RRT (P = .04). The use of amphotericin B (P = .01) or prolonged antibiotic courses (P = .04) was associated with more grades II to IV hepatic RRT. In a multivariate analysis, only amphotericin B administration predicted grades II to IV hepatic RRT (P = .01). The incidence of acute GVHD was 49%, with 31% having grades II to IV GVHD. The estimated 2-year event-free survival (EFS) for the entire study group was 44%. The estimated 2-year EFS was 63% for standard-risk patients (acute leukemia in first remission and chronic myelogenous leukemia [CML] in first stable phase) and 24% for all others (high-risk patients). High-risk patients were at increased risk of disease recurrence and RRT. BuCy is an efficacious bone marrow transplant conditioning regimen for standard-risk patients with leukemia but has significant associated hepatic RRT.

Allogeneic marrow transplantation for refractory Hodgkin's disease.

Eight patients with refractory Hodgkin's disease received intensive combination chemotherapy conditioning with cyclophosphamide, carmustine (BCNU), and etoposide (VP 16-213), and allogeneic marrow transplants. All patients achieved complete responses. Three patients relapsed; two died of Hodgkin's disease and one of chronic graft-v-host disease (GVHD) and infection. In all, four patients died due to transplant-related toxicity. One patient developed a fatal B-cell lymphoproliferative disorder soon after transplantation, and died without evidence of Hodgkin's disease. One patient is alive and free of progression 29 months after transplantation. These data indicate that allogeneic marrow transplantation may be considered as therapy for selected patients with advanced Hodgkin's disease and, despite substantial toxicity, will occasionally result in long-term responses. Better patient selection would likely improve results.

Intensive chemotherapy with cyclophosphamide, carmustine, and etoposide followed by autologous bone marrow transplantation for relapsed Hodgkin's disease.

Fifty-six consecutive patients with advanced Hodgkin's disease considered incurable with further conventional chemotherapy were entered into a protocol that included high-dose cyclophosphamide (7.2 g/m2), carmustine (BCNU; 0.6 g/m2), and etoposide (VP16-213; 2.4 g/m2) (CBV) followed by autologous bone marrow transplantation (BMT). Prior combination chemotherapy had failed in all the patients, and all but five had been previously treated with both mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) and doxorubicin, bleomycin, and vinblastine with or without dacarbazine (ABV[D]). Thirty-four eligible patients received short-course conventional chemotherapy and/or involved-field radiotherapy before CBV. However, formal restaging was not performed after these conventional therapies; ie, the therapies were not used to select responding patients for transplantation, and all who received such therapy subsequently received CBV and autologous marrow grafts. Forty-four patients (80%; 95% confidence interval [CI], 69% to 91%) achieved a complete response after CBV and BMT. Performance status at protocol entry and the use of conventional cytoreduction therapy before CBV correlated with response. Median follow-up is now 3.5 years (range, 2.5 to 5.0 years). Kaplan-Meier estimates for overall and event-free survival 5 years after transplant are 53% (95% CI, 37% to 67%) and 47% (95% CI, 33% to 60%), respectively. In a univariate analysis, patients with a normal performance status and those without constitutional ("B") symptoms at protocol entry had an improved overall and event-free survival. In a multivariate analysis, only a normal performance status remained significant. Disease progression occurred in 17 patients at an actuarial rate of 39% (95% CI; 26% to 56%) and occurred at previous sites of active disease in all but one patient; our analysis did not identify prognostic factors for progression. Toxic deaths, caused by either neutropenic sepsis or interstitial pneumonitis (IP), occurred in 12 patients (21%; 95% CI, 10% to 32%). CBV with autologous marrow support can produce durable remissions in a substantial number of patients with Hodgkin's disease considered incurable with conventional measures. Regimen refinements may even further improve the therapeutic index of BMT in this malignancy.

Role of postinduction immunotherapy in acute myeloid leukemia.

Because chemotherapy alone does not eliminate clonogenic leukemic cells, disease may recur after induction and consolidation chemotherapy. Studies of patients receiving high-dose chemotherapy supported by bone marrow or blood stem-cell transplantation suggest that immune-mediated effects of transplanted cells help control disease. This antileukemic (graft-versus-leukemia) effect represents several immune reactions. Various approaches to introduce or enhance such immune reactivity in patients with acute myeloid leukemia (AML) are being explored. There is some indication, even in older patients, that immunotherapy is better tolerated than chemotherapy, and efforts are underway to find the most effective treatment for maintaining remission after induction chemotherapy. We have developed a strategy that combines myeloablative chemotherapy with transplantation of autologous stem cells that have been cultured for 1 week in interleukin-2. Low-dose interleukin-2 is also administered for the first week after stem cell infusion. Although all patients developed side effects of fever and fatigue, even older patients tolerated this regimen well. The 3-year disease-free survival rate in a high-risk patient group transplanted in early first remission is 41 percent. Several other compounds are being investigated for their ability to enhance immune reactions after induction chemotherapy for AML. Although immunotherapy cannot eliminate overt leukemia and cytoreductive treatment is still needed initially, immunotherapy may find a place in postinduction management of AML to eliminate minimal (residual) disease or control its growth.

Characterization of a human cell line (NK-92) with phenotypical and functional characteristics of activated natural killer cells.

The cell line described here was established for a 50-year-old male patient with rapidly progressive non-Hodgkin's lymphoma whose marrow was diffusely infiltrated with large granular lymphocytes (LGL). Immunophenotyping of marrow blasts and peripheral lymphocytes was positive for CD56, CD2 and CD7, and negative for CD3. Cytotoxicity of peripheral blood mononuclear cells at an effector: target (E:T) cell ratio of 50:1 was 79% against K562 cells and 48% against Daudi cells. To establish the line, cells from the peripheral blood were placed into enriched alpha medium containing 12.5% fetal calf serum, 12.5% horse serum, 10(-4) M beta-mercaptoethanol and 10(-6) M hydrocortisone. Growth of the line (termed NK-92) is dependent on the presence of recombinant IL-2 and a dose as low as 10 U/ml is sufficient to maintain proliferation. Conversely, cells die within 72 h when deprived of IL-2; IL-7 and IL-12 do not maintain long-term growth, although IL-7 induces short-term proliferation measured by 3H-thymidine incorporation. None of the other cytokines tested (IL-1 alpha, IL-6, TNF-alpha, IFN-alpha, IFN-gamma) supported growth of NK-92 cells which have the following characteristics: surface marker positive for CD2, CD7, CD11a, CD28, CD45, CD54, CD56bright; surface marker negative for CD1, CD3, CD4, CD5, CD8, CD10, CD14, CD16, CD19, CD20, CD23, CD34, HLA-DR. DNA analysis showed germline configuration for T-cell receptor beta and gamma genes. CD25 (p55 IL-2 receptor) is expressed on about 50% of all cells when tested at 100 U/ml of IL-2 and its expression correlates inversely with the IL-2 concentration. The p75 IL-2 receptor is expressed on about half of the cells at low density irrespective of the IL-2 concentration. NK-92 cells kill both K562 and Daudi cells very effectively in a 4 h51-chromium release assay (84 and 86% respectively, at an E:T cell ratio of 5:1). The cell line described here thus displays characteristics of activated NK-cells and could be a valuable tool to study their biology.

Induction of sensitivity to NK-mediated cytotoxicity by TNF-alpha treatment: possible role of ICAM-3 and CD44.

SR-91 is a natural killer (NK)-resistant leukemic cell line expressing a low level of ICAM-1. Pre-treatment of SR-91 cells with TNF-alpha or IFN-gamma, increased both ICAM-1 (CD54) expression on SR-91 cells and binding to the human NK cell line NK-92. However, only TNF-alpha-treated SR-91 cells became sensitive to killing by NK-92 cells. The increased binding induced by both cytokines and the TNF-alpha-induced sensitivity of SR-91 cells to NK-92 cell killing were abrogated by anti-LFA-1 mAb as well as by a combination of antibodies against the three ligands of LFA-1 (CD11a/CD18), ICAM-1 (CD54), ICAM-2 (CD102) and ICAM-3 (CD50). This indicated that LFA-1 interaction with the three ICAMs on SR-91 cells is essential for effector-target cell binding (which is a prerequisite for subsequent target cell lysis), but is insufficient to render the SR-91 cells sensitive to killing by NK-92 cells. TNF-alpha, but not IFN-gamma also induced the activation of LFA-1, CD44 and beta1 integrins on SR-91 cells. Based on these observations we propose that the differential effect of TNF-alpha and IFN-gamma could be related to the activation of certain adhesion molecules on the surface of SR-91 cells by TNF-alpha that, upon interaction with their counter-receptors on NK-92 cells, lead to the activation of the NK-92 cells.

Culture of normal and leukemic bone marrow in interleukin-2: analysis of cell activation, cell proliferation, and cytokine production.

Transplantation of bone marrow autografts activated by culture in interleukin-2 (IL-2) followed by administration of IL-2 represents a novel approach in an attempt to combine ex vivo purging and post-transplant in vivo immunotherapy, and initial clinical results have suggested its feasibility. To further characterize the mechanism of the in vitro anti-leukemia effect, fresh bone marrow from normal donors and from patients with acute myelogenous leukemia (AML) in remission was cultured for 6 days in the absence or presence of IL-2 (1000 IU/ml). Proliferation of CD3, CD8, CD14, and CD56 cells was determined by direct immunofluorescence using flow cytometry. Predominantly T-lymphocytes (CD3+) and to a lesser extent CD56+ natural killer (NK) cells proliferate in 6-day marrow cultures in IL-2. Fresh bone marrow cells have no measurable NK activity when tested against K562 and Daudi target cell lines in a 4 h chromium-51 release assay, and it requires at least 6 days of culture in IL-2 to develop optimal cytotoxic activity. Cytokines released in the supernatants of these cultures were measured by immuno- and bioassays. Tumour necrosis factor alpha (TNF-alpha), interferon gamma (IFN-gamma), and IL-6 were found to be produced in significant amounts by marrow mononuclear cells during culture in IL-2. Even without IL-2 present, concentrations of these cytokines were increased in 6-day marrow cultures. In contrast, IL-3, IL-7, granulocyte and granulocyte-macrophage colony-stimulating factors (G-CSF and GM-CSF) were below the level of detection of the immunoassay, a result that could be confirmed for GM-CSF and IL-3 by bioassay. The data suggest that culture of marrow from normal donors as well as from patients with AML obtained in remission can generate anti-leukemia effector mechanisms which are non-crossreactive with chemo- and radiotherapy and may contribute to effective ex vivo purging of residual leukemic cells. The transplantation of such IL-2 'primed' marrow may also contribute to an in vivo graft-versus-leukemia effect.

Response of therapy-related myelodysplasia to low-dose interleukin-2.

We report the case of a patient treated with interleukin-2 (IL-2) for refractory anemia with excess blasts (RAEB), which developed during third complete remission of acute lymphoblastic leukemia. IL-2 was given subcutaneously at 2.5 x 10(5) IU (= 10(5) BRMP units) twice daily for 30 days. During treatment spontaneous natural killer (NK) activity was enhanced, circulating lymphokine-activated killer effector cells became detectable and CD56+/CD3- NK cells in the blood doubled. The response in the bone marrow was a reduction in myeloid blast cells (from 7 to 0%), ringed sideroblasts (from > 15 to 0%) and dysplasia (from trilineage to minimal megakaryocytic), and a decrease in metaphases with the RAEB karyotype (from 43 to 2%). Toxicity of IL-2 was minimal. Thus a relatively low dose of IL-2 caused immune activation and resulted in significant hematologic and cytogenetic response in this case of therapy-related myelodysplasia.

Antileukemia activity of a natural killer cell line against human leukemias.

We describe here the in vitro and in vivo antileukemia activity of a recently described natural killer (NK) cell line (NK-92), which has features of human activated NK cells. The cytotoxic activity of rhIL2-dependent cultured NK-92 cells against primary patient-derived leukemic target cells [12 acute myelogenous leukemias (AMLs), 7 T acute lymphoblastic leukemias (T-ALLs), 14 B-lineage-ALLs, and 13 chronic myelogenous leukemias (CMLs)], human leukemic cell lines (K562, KG1, HL60, Raji, NALM6, TALL-104, CEM-S, and CEM-T) and normal bone marrow cells was measured in 51Cr-release assay (CRA). The patient-derived leukemias could be subdivided into three groups based on their sensitivity to NK-92 cells: insensitive (< or =19% lysis), sensitive (20-49% lysis), and highly sensitive (> or =50% lysis) at an E:T ratio of 9:1. Of 46 patient-derived samples, 24 (52.2%) were sensitive or highly sensitive to NK-92-mediated in vitro cytotoxicity (6 of 12 AMLs, 7 of 7 T-ALLs, 5 of 14 B-lineage-ALLs, and 6 of 13 CMLs). NK-92 cells were highly cytotoxic against all of the eight leukemic cell lines tested in a standard 4-h CRA. Normal human bone marrow hematopoietic cells derived from 18 normal donors were insensitive to NK-92-mediated cytolysis. In comparison with human lymphokine-activated killer cells, normal NK cells, and T cells, NK-92 cells displayed more powerful antileukemia activity against a patient-derived T-ALL as well as K562 and HL60 cells, both in in vitro CRA and in a xenografted human leukemia SCID mouse model. The NK-92 cells did not induce the development of leukemia in SCID mice after i.v., i.p., or s.c. inoculation. In adoptive transfer experiments, SCID mice receiving i.p. inoculations of human leukemias derived from a T-ALL (TA27) and an AML (MA26) that were highly sensitive to the cytolysis of NK-92 cells in vitro, as well as a pre-B-ALL (BA31) that was insensitive to the in vitro cytolysis of NK-92 cells, were treated by administration of NK-92 cells with or without rhIL2 (2 x 10(7) NK-92 cells i.p.; one dose or five doses). Survival times of SCID mice bearing the sensitive TA27 and MA26 leukemias were significantly prolonged by adoptive cell therapy with NK-92 cells. Some of the animals who received five doses of NK-92 cells with or without rhIL2 administration were still alive without any signs of leukemia development 6 months after leukemia inoculation. In contrast, survival of mice bearing the insensitive BA31 leukemia were not affected by this treatment. This in vitro and in vivo antileukemia effect of NK-92 cells suggests that cytotoxic NK cells of this type may have potential as effectors of leukemia control.

Involvement of fibronectin and its receptor in human lymphocyte proliferation.

Adhesion between lymphocytes and antigen-presenting cells is necessary for the development of certain immune reactions. We have previously shown that fibronectin (FN) added to mixed lymphocyte cultures (MLC) can restore a decreased lymphocyte proliferation in immunocompromised individuals. Using highly purified cell populations from peripheral blood for depletion and adding back experiments we show here that exogenous FN enhanced proliferation only when allogeneic monocytes were co-cultured with responder lymphocytes. Although lymphocyte proliferation in MLC was augmented by FN, there was no preferential proliferation of any particular major lymphocyte subpopulation in cultures supplemented with FN as compared to control cultures lacking its addition. Antibody against the FN receptor (FN-R) of the beta 1 integrin family, as well as Arg-Gly-Asp containing peptide, could inhibit alloantigen-induced lymphocyte proliferation in a concentration-dependent manner. Anti-CD3-induced proliferation was inhibited by anti-FN-R antibody but not Arg-Gly-Asp peptide whereas no inhibition was seen with the phytohemagglutinin (PHA)-induced lymphocyte proliferation. This study presents further evidence that FN and its receptor (alpha 5 beta 1) are involved in the augmentation of T-cell responsiveness to proliferative stimuli.

Fibronectin is present on B-cells but not on OKT 3-positive T-lymphocytes or Leu 11-positive natural killer cells.

We examined T-cells, B-cells, and natural killer cells of four normal individuals for surface-bound fibronectin (FN) using fluorescence-activated cell sorter analysis and double fluorescence labeling with monoclonal antibodies. While Leu 12 (CD 19)-positive B-cells stained also uniformly with anti-FN antibody, neither OKT 3 (CD 3)-positive T-cells nor Leu 11 (CD 16)-positive natural killer cells could be labeled with anti-FN. Although an anti-FN receptor antibody was not available, these data strongly suggest a distinct pattern of FN-binding by human lymphocytes.

Inhibition of cluster formation and lymphocyte proliferation by anti-fibronectin antiserum.

Dendritic cells (DC) confer concanavalin A responsiveness to accessory cell-depleted canine lymphocytes. DC-lymphocyte cluster formation is followed by blast transformation and proliferation of lymphocytes. We investigated whether fibronectin, which is known to be involved in cell:cell interactions, might also be involved in the interaction between canine DC and lymphocytes. The addition of rabbit anti-dog fibronectin antiserum to concanavalin A-stimulated peripheral blood mononuclear cells decreased cluster formation and reduced 3H-thymidine incorporation by 57-70%. Similarly, when cell fractions, enriched for DC, were pretreated with anti-fibronectin antiserum before being added back to accessory cell-depleted lymphocytes, cluster formation was reduced and lymphocyte proliferation after concanavalin A stimulation decreased by 18-46% as measured by 3H-thymidine uptake. Ferritin-conjugated anti-fibronectin antibody was bound to the surface of DC, primarily at the dendritic processes. We conclude that fibronectin, located on the surface of canine DC, participates in the accessory cell function of these cells.

Regulation of fibronectin receptor (alpha 5 beta 1) mRNA expression in human monocytes and monocyte-derived macrophages by activation/differentiation signals.

Members of the beta 1 subfamily of integrins, a group of heterodimeric transmembrane adhesion receptors, mediate the attachment of monocytes and macrophages to cell matrix proteins such as fibronectin, collagen, and laminin. Such interactions are likely of considerable importance during inflammatory responses, when monocytes are recruited to, and retained in, extravascular sites. Because of the complexity of the interactions that befall monocytes during an inflammatory response, it seems likely that expression of adhesion receptors on monocytes would be precisely regulated. In the present study, we have examined the mRNA expression of alpha 5 and beta 1 subunits of the fibronectin receptor in purified human peripheral blood monocytes and monocyte-derived macrophages cultured in the absence or presence of various agents known to induce activation and/or differentiation. Incubation under nonadherent conditions for 6 h with interferon (IFN)-gamma or bacterial lipopolysaccharide (LPS) resulted in a decreased expression of both alpha 5 and beta 1 mRNAs in freshly isolated monocytes. In contrast, incubation with IFN-alpha did not result in a decreased expression of alpha 5 mRNA, although a moderate decrease in beta 1 mRNA was observed. Culture with granulocyte-macrophage colony-stimulating factor, macrophage colony-stimulating factor, phorbol myristic acetate, or plasma fibronectin (under nonadherent and adherent conditions) did not result in a change in levels of alpha 5 or beta 1 transcripts. In contrast to the results obtained with freshly isolated monocytes, incubation for 6 h with IFN-gamma or LPS did not alter the expression of alpha 5 or beta 1 mRNA in macrophages derived by culture of monocytes for 6 days in Teflon beakers. Our results indicate that IFN-gamma and LPS, both of which may be present in inflammatory sites, downregulate the mRNA expression of fibronectin receptor subunits in monocytes. Moreover, alpha 5 and beta 1 gene regulation by these agents is apparently dependent on the differentiation stage of the cells. This may provide a mechanism by which extravasating monocytes detach from extracellular matrix proteins, present in subendothelial basement membranes and deposited in sites of inflammation, in order to pursue other activities.

Design and validation of a clinically applicable culture procedure for the generation of interleukin-2 activated natural killer cells in human bone marrow autografts.

Previous studies in animal models have suggested that bone marrow-derived interleukin-2 (IL-2) activated natural killer (A-NK*) cells can be used to eliminate residual leukemic cells both in vivo and in vitro. As part of initial studies to develop a clinical protocol to exploit this phenomenon in combination with culture purging of leukemic cells, we examined a number of variables that might affect either IL-2 stimulation of natural killer (NK) cell activity or maintenance of primitive hematopoietic cells in cultures suitable for manipulating human marrow autografts. Cytotoxicity of IL-2 A-NK cells was determined using K562 and Daudi target cells in a standard 4-hour 51Cr release assay. Primitive hematopoietic cells were quantitated using both direct clonogenic progenitor assays and the long-term culture-initiating cell (LTC-IC) assay. The latter measures a very primitive cell type that gives rise to clonogenic cells after > 5 weeks of culture on pre-established marrow feeder layers. Light-density (< 1.070 g/cm3) human marrow cells cultured at 10(6) cells/mL for 7 days at 37 degrees C in the presence of 1000 U of either natural or recombinant human IL-2 showed a marked generation of A-NK cell function that was not seen if IL-2 was not added. The cytotoxicity was the same whether the cells had been maintained in standard fetal calf serum (FCS)-supplemented medium or in LTC medium (which also contains horse serum and 10(-6) M hydrocortisone) or whether adherence of cells during the culture period was promoted or prevented. The level of NK activity in IL-2-stimulated cultures of marrow cells from patients with acute myeloid leukemia (AML) in remission was not significantly different from that obtained with normal marrow. The initial numbers of clonogenic cells in these samples were close to normal values (60%). For both normal and AML patient samples, these declined slightly during the 7-day culture period, regardless of whether IL-2 was present. Starting values for LTC-IC in patient marrow samples were markedly reduced to approximately 7% of normal values, but as in normal cultures, did not decrease further in culture with or without IL-2. These results indicate that activation of bone marrow-derived NK cells can be obtained in 7-day cultures containing IL-2 under conditions that preserve the most primitive hematopoietic cells currently detectable.

Characterization of genetically altered, interleukin 2-independent natural killer cell lines suitable for adoptive cellular immunotherapy.

NK-92 is a highly cytotoxic natural killer (NK) tumor cell line that possesses properties that make it an excellent candidate for adoptive cellular immunotherapy. However, the cytotoxicity of NK cells is dependent on cytokines such as interleukin 2 (IL-2). Although NK-92 cells maintain cytotoxicity for a time after withdrawal of IL-2, clinical use will probably require prolonged treatment with fully activated cells to eliminate disease effectively. The ability to support cytotoxic cells with exogenously administered IL-2 is limited by associated toxicity. Therefore, we describe the transfection of the IL-2-dependent NK-92 cell line with human IL-2 (hIL-2) cDNA by particle-mediated gene transfer to create two IL-2-independent variants, NK-92MI and NK-92 CI, and describe their characterization and comparison with parental cells. Both variants were shown to contain, express, and synthesize the hIL-2 cDNA. IL-2 synthesis was higher in NK-92MI cells compared with NK-92CI cells, with no expression in parental cells. Functionally, the cytotoxicity of all three cell lines was similar and coincubation with IL-2-independent variants did not affect hematopoietic progenitor cells. NK-92MI and NK-92CI cells were more radiosensitive than NK-92 cells, with proliferation inhibited at lower radiation doses and increased morality and decreased cytotoxicity compared with parental cells. Data presented here show that we have created by particle-mediated gene transfer two IL-2-independent variants of NK-92 that are identical to parental cells in virtually all respects, including high cytotoxic activity. The nonviral transfection of these cells makes them suitable for clinical applications. These IL-2-independent cells should allow prolonged treatment with fully active natural killer cells without the need for exogenous IL-2 support.

Phenotypical and functional studies on a subtype of suppressor cells (CD8+/CD11+) in patients after bone marrow transplantation.

Dual labeling with the monoclonal antibodies anti-Leu 2 (fluorescein-conjugated) and anti-Leu 15 (phycoerythrin-conjugated) was used to phenotype and sort the lymphocytes from 12 short-term (100 days postgrafting) recipients, 8 long-term (6 months postgrafting) stable, and 11 long-term patients with chronic graft-versus-host disease (GVHD). The proportion of Leu 2+ 15+ cells was increased in 11 of 12 short-term patients (mean + SEM: 31% +/- 3.6)-and in 6 of 11 patients with chronic GVHD (18% +/- 2.4) compared with normal controls (n = 8; 7.5% +/- 1.9). However, there was no correlation between proportions of Leu 2+ 15+ or Leu 2+ 15- cells and the presence of acute GVHD. Long-term patients with chronic GVHD tended to have a higher proportion of Leu 2+ 15- cells. To functionally characterize these two T cell subsets, Leu 2+ 15- and Leu 2+ 15+ subsets were sorted from purified T cells obtained from two recipients and one normal subject. Both Leu 2+ 15+ and Leu 2+ 15- cells from a short-term patient suppressed pokeweed mitogen--stimulated immunoglobulin production of normal B cells. Leu 2+ 15- cells from a long-term survivor with chronic GVHD and the normal control provided help, whereas the Leu 2+ 15+ cells also strongly suppressed immunoglobulin synthesis. The suppressor activity of the Leu 2+ 15+ subset in all three individuals was radiosensitive (12 Gy). These results illustrate the need for careful correlative phenotyping and functional studies. Furthermore, these studies clearly demonstrate that different functions may exist within a particular T cell phenotype after bone marrow transplantation.

Fibronectin restores defective in vitro proliferation of patients' lymphocytes after marrow grafting.

In search for means of improving the impaired lymphocyte function of recipients after marrow grafting, we investigated the effect of fibronectin (FN) on patients' lymphocytes in allogeneic mixed lymphocyte cultures (MLC) and in cell-mediated lympholysis (CML) assays, since these tests are usually defective in transplanted patients. Four subgroups of marrow recipients were tested: patients within the first 100 days of transplantation (short-term) with (n = 16) or without (n = 14) acute graft-versus-host disease (GVHD), and long-term recipients with (n = 23) or without (n = 15) chronic GVHD. Exogenous FN (25 micrograms/ml) increased the proliferative response in the allogeneic mixed lymphocyte culture (MLC) significantly in cells from short-term patients without acute GVHD (+42%) and in those from long-term recipients with (+117%) and without chronic GVHD (+48%). In cells from patients with chronic GVHD, 3H-thymidine uptake after the addition of FN was enhanced to the level of that in lymphocytes of the corresponding marrow donor without exogenous FN. Fibronectin was effective only if added at the beginning of the MLC. In contrast to the results in MLC, exogenous FN failed to enhance phytohemagglutinin or OKT-3-induced lymphocyte proliferation and had no effect on CML activity. Moreover, FN did not show mitogenic activity in 3-6-day cultures. Our results demonstrate that FN in vitro is capable of restoring defective lymphocyte proliferation in marrow grafted patients, and circumstantial evidence suggests that this effect is mediated by an interaction between FN and monocytes.

Fibronectin receptor subunit (alpha 5, alpha 4 and beta 1) mRNA and cell surface expression in human peripheral blood B lymphocytes.

Members of the beta 1 family of heterodimeric adhesion molecules, e.g., the fibronectin receptors alpha 5 beta 1 and alpha 4 beta 1, mediate the binding of leukocytes to extracellular matrix proteins and may also support cell-cell interactions important for homing and localization of leukocytes at sites of immune and inflammatory reactions. In the present investigation, we have examined human peripheral blood B lymphocytes for mRNA and cell surface expression of fibronectin receptor subunits. B cells (CD 19-positive cells) expressed alpha 4 and beta 1, but not alpha 5, on their surface as determined by double immunofluorescence staining. Highly purified B cells, sorted on the basis of lymphocyte light scatter characteristics and the presence of surface IgM, expressed alpha 4, beta 1 and alpha 5 mRNAs. Expression of integrins, such as alpha 4 beta 1, on B lymphocytes may be important for cell-cell interactions that occur during immune responses.