MnTMPyP, a metalloporphyrin-based superoxide dismutase/catalase mimetic, protects INS-1 cells and human pancreatic islets from an in vitro oxidative challenge.

AIMS: Pancreatic islets can be lost early following allotransplantation from oxidative stress. Antioxidant enzyme overexpression could confer a beneficial effect on islets exposed to reactive oxygen species (ROS) and nitrogen species. Here, we tested the effect of MnTMPyP, a superoxide dismutase/catalase mimetic. METHODS: INS-1 insulin-secreting cells or human islets were cultured with MnTMPyP and exposed to a superoxide donor (the hypoxanthine/xanthine oxidase (HX/XO) system), a nitric oxide donor [3-morpholinosydnonimine (SIN-1)] or menadione. Viability of INS-1 cells was assessed by WST-1 colorimetric assay and FACS analysis (Live/Dead test). ROS production was determined using fluorescent probes. Islet viability was estimated by WST-1 assay and endocrine function by static incubation. RESULTS: Following MnTMPyP treatment, ROS production in INS-1 cells was reduced by 4- to 20-fold upon HX/XO challenge and up to 2-fold upon SIN-1 stress. This phenomenon correlated with higher viability measured by WST-1 or Live/Dead test. MnTMPyP preserved islet viability upon exposure to SIN-1 or menadione but not upon an HX/XO challenge. Similarly, decrease in insulin secretion tended to be less pronounced in MnTMPyP-treated islets than in control islet when exposed to SIN-1, but no changes were noticed during an HX/XO stress. CONCLUSIONS: MnTMPyP was able to improve the viability of INS-1 cells and human islets exposed to oxidative challenges in vitro. Protection of INS-1 cells could be as high as 90%. This agent is therefore potentially attractive in situations involving the overproduction of ROS, such as islet transplantation.

Mesenchymal stem cells induce apoptosis of activated T cells.

Mesenchymal stem cells (MSC) have recently been used successfully in humans to control severe graft-versus-host disease. However, the mechanisms involved in their immunomodulatory effects remain a matter of debate. Here, we show that MSC are unable to activate allogeneic T cells even in the presence of T-cell growth factors. We then found that MSC inhibit T-cell proliferation triggered either by allogeneic, mitogenic or antigen-specific stimuli. Interestingly, MSC inhibit T-cell proliferation by inducing apoptosis of activated T cells, but have no effect on resting T cells. Furthermore, we show that this apoptosis could be related to the conversion of tryptophan into kynurenine by indoleamine 2,3-dioxygenase expressed by MSC in the presence of IFNgamma. Moreover, we show that the inhibitory effect of MSC is neither abrogated nor modified during expansion in culture or after irradiation. Together, these results bring new insight to the mechanisms of immunosuppression induced by MSC and might help to develop their clinical use controlling immune-related adverse effects in humans.

Establishment of lymphomatous cell lines from bone marrow samples from patients with Burkitt's lymphoma.

A total of 233 bone marrow aspirates were obtained from 43 patients with Burkitt's lymphoma (BL). Lymphoma cells were absent and lymphoblastoid cell lines could not be established from 197 samples, which were characterized by limited initial cell proliferation and development of an adherent population, followed by cell death after 2-4 weeks. In 14 aspirates, after a similar pattern of growth, cell proliferation began again after about 6 weeks, with a rapid appearance and growth of cell clumps from the feeder layer--a type of growth typical of spontaneous lymphoblastoid cell lines. In 22 aspirates, growth of malignant cells was observed in culture and cytocentrifuged, stained smears, including marrow samples from 9 patients in whom the presence of BL cells had not been ascertained or even suspected by cytology. Karyotypic anomalies characteristic of BL were found in these cells: t(8;14) in the majority, two t(8;22), two t(2;8), and one t(2;8;9).

Distinct reactivity of Burkitt's lymphoma cell lines with eight monoclonal antibodies correlated with the ethnic origin.

Twenty-eight Burkitt's lymphoma(s) (BL) cell lines were analyzed with anti-human immunoglobulins and monoclonal antibodies: Y29/55, B1, and BA1 are slightly different pan-B-reagents; TU1 and BL13 are two discriminating markers of the follicle; RFT1 is a pan-T-reagent expressed on the follicle mantle; AL2 reacts with the common acute lymphoblastic leukemia antigen gp100; and 38:13 recognizes a BL-associated antigen. Those lines were classified into 3 groups according to their membrane phenotype. In the first 2 groups, cell lines were derived from BL of germinal center origin, whereas in the last group they were established from BL cells originating in the bone marrow. All cell lines in the last group were from Caucasian BL, whereas lines from African BL of a high-incidence area were in group 1. North African cases were in group 2. Those distinct subgroups were not related specifically to the reactivity with Epstein-Barr virus nuclear antigen, the type of chromosomal translocation, or the clinical features. The variations induced by growth culture as well as the clinical implications were discussed.

[Diagnosis of lung cancer. DNA microarrays in thoracic oncology]. / Diagnostic des CBP. Les "puces à ADN" en oncologie thoracique.

DNA microarrays allow simultaneous measurement of the expression of several thousand genes in a biological specimen. This technique represents a major advance in the analysis of tumour biopsies. It may be used to refine the anatomical- pathological diagnosis at a molecular level and thus lead to better diagnostic and prognostic classification and improved therapeutic decisions.

Tumor necrosis factor as an autocrine growth factor for neuroblastoma.

Recombinant tumor necrosis factor (TNF) stimulates the proliferation of two neuroblastoma cell lines, SKNFI and SKNBE, in both serum-free medium and fetal calf serum-supplemented medium but has no effect in medium without insulin. This effect is very similar with TNF doses ranging from 5 to 500 ng/ml but depends on the duration of treatment; when cells are treated for 168 h with TNF, the maximal index of proliferation is observed between 120 and 144 h of treatment. The two neuroblastoma cell lines express type A and type B TNF receptors and contain TNF protein; however, TNF is undetectable in culture supernatants. Treatment of the two neuroblastoma cell lines with a rabbit polyclonal antibody to TNF for 96 h fully inhibits [3H]thymidine incorporation; less than 5% viable cells are left in the samples after treatment. A combination of two monoclonal antibodies against type A and type B TNF receptors also inhibits over 85% of the [3H]thymidine incorporation by the two cell lines after 96 h of treatment; the use of a single antibody has a partial effect, suggesting that both receptors are functional on the neuroblastoma cell lines. Taken together, these results show that TNF is an autocrine growth factor for the two neuroblastoma cell lines SKNFI and SKNBE. The results described above have been confirmed on two other neuroblastoma cell lines, IRM32 and CLB-PE.

Interleukin (IL)-10 and IL-6 are produced in vivo by non-Hodgkin's lymphoma cells and act as cooperative growth factors.

The in vivo production of interleukin (IL)-10, IL-6, IL-2, and tumor necrosis factor (TNF)-alpha in tumor samples was investigated by immunohistochemistry in 54 non-Hodgkin's lymphomas (NHLs). Respectively, 55, 89, 23, and 29% of tumor samples were found positive for IL-10, IL-6, IL-2, and TNF-alpha expression by immunohistochemistry. Using reverse transcription-PCR, the mRNA of IL-10 and IL-6 were detectable in all samples tested and in 90 and 34% of the samples for TNF-alpha and IL-2, respectively. In 13 patients, fresh tumor tissue was available for B NHL cell purification with Dynabeads. IL-10, IL-6, IL-2, and TNF-alpha were detectable in the supernatant of 38, 100, 0, and 23% of purified tumor cell preparations (PTCPs), respectively. All patients with detectable IL-10 in culture had increased serum IL-10. IL-6 production by tumor cells and serum IL-6 levels were also found to be highly correlated (P < 0.0001). This suggests that tumor cells are a major source of serum IL-1O and IL-6 in these patients. Exogenous IL-10, IL-6, IL-2, and TNF-alpha significantly enhanced the [3H]thymidine uptake in 13 of 13 (100%), 5 of 13 (38%), 9 of 13 (69%), and 2 of 10 (20%) PTCPs costimulated with anti-CD40, respectively. IL-2, IL-6, and TNF-alpha synergized with IL-10 in 54, 23, and 30% of PTCPs. The combination of IL-10, IL-2, and IL-6 induced the maximal level of proliferation in 12 (92%) of 13 PTCPs. CD40 ligand mRNA expression was also detectable in vivo using reverse transcription-PCR in 28 of the 29 (97%) tumor samples tested, including 11 of those tested for [3H]thymidine incorporation. These results show that IL-1O, IL-6, IL-2, and TNF-alpha are produced in NHL tumors and may cooperate in vivo to increase NHL cell proliferation.

Correlation between clinical response to interleukin 2 therapy and sustained production of tumor necrosis factor.

Twenty-five previously untreated patients with metastatic renal cell carcinoma were treated with 5-day cycles of continuous infusion of interleukin 2 (IL2) and lymphokine-activated killer cell reinfusion. Five achieved a partial response. Three patients were found to have detectable tumor necrosis factor (TNF) in serum before initiation of therapy. On the fifth day of therapy, 24 patients had circulating TNF with immunoradiometric assay whereas 13 had detectable biological activity. Two days after the end of IL2 therapy, TNF concentration (immunoradiometric assay) decreased in most cases but was still detectable in 17 patients. Thirteen patients had still circulating TNF bioactivity. Although there was no significant difference between TNF levels observed on the fifth day of therapy in the responder and nonresponder groups, 48 h after the end of IL2 infusion, both the TNF concentration and the biological activity were significantly higher in the group of responder patients. This result suggests that the clinical response to IL2 therapy in patients with metastatic renal cell carcinoma is correlated to a sustained production of TNF after the end of IL2 infusion.

Clinical relevance of CD44 cell-surface expression and N-myc gene amplification in a multicentric analysis of 121 pediatric neuroblastomas.

PURPOSE: In contrast to other human tumors, a repression of the cell-surface glycoprotein CD44 on neuroblastoma is a marker of aggressiveness that usually correlates to N-myc amplification. We thus compared the prognostic value of both markers in the initial staging of 121 children treated for neuroblastoma in collaborative institutions. METHODS: Frozen samples were analyzed by a rapid and well-standardized technique of immunostaining with monoclonal antibodies (MoAbs) against epitopes in the CD44 constant region. RESULTS: In this retrospective series, CD44 was expressed on 102 specimens and strongly correlated with favorable tumor stages and histology, younger age, and normal N-myc copy numbers. In univariate analysis, CD44 expression and normal N-myc were the most powerful markers of favorable clinical outcome (P < 10(-6) and chi 2 = 65.40 and P < 10(-6) and chi 2 = 42.56, respectively), but analysis of CD44 affords significant prognostic discrimination in subgroups of patients with or without N-myc-amplified tumors. In the subgroup of stage IV neuroblastomas, CD44 was the only significant prognostic marker (P < .02, chi 2 = 5.76), whereas N-myc status was not discriminant. In multivariate analysis of five factors, ie, N-myc amplification, CD44 expression, age, tumor stage, and histology, the only independent prognostic factors of event-free survival were CD44 expression and tumor stage. CONCLUSION: The analysis of CD44 cell-surface expression must be recommended as an additional biologic marker in the initial staging of the disease.

International criteria for diagnosis, staging, and response to treatment in patients with neuroblastoma.

Neuroblastoma is one of the most common tumors in childhood. However, it often has been difficult to compare clinical and laboratory studies of this disease due to a lack of uniform criteria for diagnosis, staging, and response. An international group of conferees addressed each of these issues and reached a consensus. Specific criteria for making a diagnosis of neuroblastoma are defined. A new neuroblastoma staging system is proposed that takes into account the most important elements of current but incompatible systems. Finally, criteria for response to treatment are standardized. The criteria proposed herein represent an international consensus of essentially every major pediatric oncology group or organization in the United States, Europe, and Japan. The staging system should be referred to as the International Neuroblastoma Staging System, and the response criteria as the International Neuroblastoma Response Criteria. Implementation of these criteria will greatly facilitate the comparison of clinical and laboratory studies by different groups and countries. Furthermore, these criteria should serve as a foundation on which future modifications or improvements can be based.

Revisions of the international criteria for neuroblastoma diagnosis, staging, and response to treatment.

PURPOSE AND METHODS: Based on preliminary experience, there was a need for modifications and clarifications in the International Neuroblastoma Staging System (INSS) and International Neuroblastoma Response Criteria (INRC). In 1988, a proposal was made to establish an internationally accepted staging system for neuroblastoma, as well as consistent criteria for confirming the diagnosis and determining response to therapy (Brodeur GM, et al: J Clin Oncol 6:1874-1881, 1988). A meeting was held to review experience with the INSS and INRC and to revise or clarify the language and intent of the originally proposed criteria. Substantial changes included a redefinition of the midline, restrictions on age and bone marrow involvement for stage 4S, and the recommendation that meta-iodobenzylguanidine (MIBG) scanning be implemented for evaluating the extent of disease. Other modifications and clarifications of the INSS and INRC are presented. In addition, the criteria for the diagnosis of neuroblastoma were modified. Finally, proposals were made for the development of risk groups that incorporate both clinical and biologic features in the prediction of prognosis. The biologic features that were deemed important to evaluate prospectively included serum ferritin, neuron-specific enolase (NSE), and lactic dehydrogenase (LDH); tumor histology; tumor-cell DNA content; assessment of N-myc copy number; assessment of 1p deletion by cytogenetic or molecular methods; and TRK-A expression. RESULTS AND CONCLUSION: Modifications of the INSS and INRC made at this conference are presented. In addition, proposals are made for future modifications in these criteria and for the development of International Neuroblastoma Risk Groups.

N-Myc gene amplification is a major prognostic factor in localized neuroblastoma: results of the French NBL 90 study. Neuroblastoma Study Group of the Société Francaise d'Oncologie Pédiatrique.

PURPOSE: To assess the relevance of N-Myc gene amplification (NMA) as a prognostic factor in localized neuroblastoma (NB) and to evaluate whether less intensive adjuvant treatment is advisable in infants without NMA. PATIENTS AND METHODS: Assessment of NBs included clinical and imaging data to allow tumor-node-metastasis (TNM) staging, biologic determinations (N-Myc gene analysis), and standard histology and work-up to eliminate metastatic spread (metaiodobenzylguanidine [MIBG] scintigraphy and extensive bone marrow staging). Resectability was defined according to imaging findings. Chemotherapy was indicated in children older than 1 year at diagnosis who had postoperative residual disease or lymph node (LN) involvement, in infants with NMA, or as primary treatment in children with an unresectable NB, including dumbbell tumors. Radiotherapy was recommended in children older than 1 who presented with persistent gross residual disease at the end of therapy. RESULTS: Between 1990 and 1994, 316 consecutive children who presented with a localized NB were registered in the NBL 90 study. The median age was 12 months, and 42 patients had dumbbell tumors (13%). NMA was found in 22 of 225 assessable children (10%) and correlated with adverse prognostic indicators such as age older than 1 year, an abdominal primary tumor, a large tumor (T3), and unresectability. Among 186 children who had primary excision, five died of surgery-related complications. Primary chemotherapy was given to 130 patients, which allowed removal of the tumor in all but four. The 5-year overall survival (OS) and event-free survival (EFS) rates were, respectively, 91% and 84% with a median follow-up time of 36 months. The outcome of infants and older children was similar (P = .2). EFS of patients with resectable tumors was slightly better than with unresectable primary tumors (EFS, 89% v 78%; P = .02). In dumbbell NBs, neurologic recovery was achieved in 74% of cases that presented with symptoms, and initial laminectomy was avoided in 75% of children. In a univariate analysis, large tumors, high neuron-specific enolase (NSE) and lactate dehydrogenase (LDH) levels, positive LNs, macroscopic residue, and NMA adversely influenced outcome. In the multivariate analysis, NMA was the most powerful unfavorable predictive indicator: OS and EFS rates for these children were 36% and 32%, compared with 98% and 90% in nonamplified tumors (P < .001). CONCLUSION: Our data confirm the overall good prognosis of localized NBs, even when unresectable. NMA is the most relevant adverse prognostic factor in localized NBs, and more intensive treatment should be investigated in these patients. Prospective studies of other biologic factors are warranted to tailor therapy more accurately. The EFS of children who underwent primary surgery was excellent, and further justifies elimination of adjuvant treatment provided they have no NMA. Despite the elimination of postoperative therapy, infants with non-NMA tumors have an excellent outcome, which suggests that initial chemotherapy can be further reduced in case of unresectable NBs.

Promoter methylation of genes in bronchial lavages: a marker for early diagnosis of primary and relapsing non-small cell lung cancer?

A prospective screening program, including CT, autofluorescent bronchoscopy, biopsies and bronchial lavage (BL) collection, was initiated with the specific goal of identifying biomarkers for the early detection of non-small cell lung cancer. We report and discuss the results of p16, DAPK, MGMT, FHIT and APC methylation analysis in the 126 first patients: 77 at high risk of cancer and 49 followed up after primary cancer resection. Positive results were found in 49% of BLs, 53% in current smokers and 43% in former smokers. In presence of peripheral tumours, only 38% of BLs were abnormal versus 73% in presence of central tumours, 50% in presence of preneoplasic lesions and 47% in absence of lesions. FHIT methylation was an early event, observed in one-third of the BLs from patients with or without lesions as well as in tumours. APC methylation was a late event observed in 33% of tumours but rarely in BLs. p16 was methylated in 17% of BLs but in 48% of tumours; DAPK in 15% of BL and 22% of tumours. MGMT methylation was rare. Among patients followed up after cancer surgery, 14 were in remission with normalised BL, whereas three had positive BLs and relapsed with a central tumour. Thus, gene methylation in BL might help to detect central tumours but a CT is crucial for peripheral cancer detection.

Lectin-binding properties of Burkitt's lymphoma cell lines: application to bone marrow purging.

The efficacy of binding of several lectins to different Burkitt's lymphoma (BL) cell lines was investigated. Soybean agglutinin (SBA), peanut agglutinin (PNA), wheat germ agglutinin (WGA), and Sambucus nigra agglutinin (SNA) bound strongly to all BL cell lines. Because SBA has been used safely in clinical bone marrow transplantation (BMT) as part of the procedure for T-cell depletion and hence does not bind to the stem cells, we chose this lectin to establish a model for purging BL cells from human bone marrow. Using a two-step purging procedure with tumor cell agglutination by SBA in solution, a 2-log depletion could be accomplished. Using SBA-coated magnetic beads, we could improve BL cell depletion to greater than 4 logs. Because SBA seems to have a broad specificity for BL cells with concomitant enrichment in hematopoietic progenitor cells, the use of SBA-coated magnetic beads could be of interest for autologous BMT for lymphomas as well as other hematological malignancies and solid tumors with positive binding to SBA.

Retroviral gene therapy and its application in oncohematology.

A symposium entitled "Foetal and Neonatal Cell Transplantation and Retroviral Gene Therapy" recently organized under the aegis of the Mérieux Foundation in Annecy, France, brought together 100 scientists and clinicians from European countries and the United States. The last day of the meeting focused on retroviral gene therapy in oncohematology. The speakers provided the basis for therapeutic applications of gene transfer and showed practical directions to be followed in the near future. Although it may be mainly restricted to in vitro manipulation of human cells at start, gene therapy is already applicable to the treatment of genetic disorders, cancer, and viral infections. The reality of gene therapy was well illustrated by the nature of the questions raised by clinicians and scientists during the meeting.

In vivo delivery to tumors of DNA complexed with linear polyethylenimine.

Synthetic gene delivery vectors have shown promise in several organs, including brain and lung. Tumor cell targeting, however, is still hindered by their low efficacy. A linear polyethylenimine (L-PEI, Exgen 500) was found to be effective in vivo. Our first attempts to use L-PEI for intratumoral gene delivery were not successful, presumably because of poor diffusion of the complexes within the tumor mass after injection with a syringe. Here we show that L-PEI-mediated transfection can be strongly enhanced when the complexes are delivered slowly into a solid tumor mass, using a micropump. Furthermore, L-PE/DNA complexes actively transfect pseudocystic tumor cells when injected into the cyst cavity. In both cases L-PEI induced a significant and long-lasting (> or =15 days) expression of the reporter gene. Finally, even though systemic delivery of L-PEI/DNA complexes leads to high levels of expression in the lung, this method is not adapted for transfection of subcutaneous tumors implanted in the thigh nor for transfection of lung metastases. Altogether, these results show that L-PEI has promising features for transfection of tumor cells, provided that the mode of delivery is adapted.

Canarypox virus-mediated interleukin 12 gene transfer into murine mammary adenocarcinoma induces tumor suppression and long-term antitumoral immunity.

The antitumoral activity of recombinant canarypox virus vectors (ALVAC) expressing murine interleukin 12 (IL-12) was evaluated in the syngeneic, nonimmunogenic murine mammary adenocarcinoma model (TS/A). Seven-day preestablished subcutaneous tumors (5- to 6-mm mean diameters) were injected on days 7, 10, 14, 17, 21, and 24 with the vector ALVAC-IL12 at 2.5 x 10(5) TCID50 (50% tissue culture infective dose). Total tumor regression occurred in 40 to 50% of the treated mice. Furthermore, 100% of the cured mice were protected against a contralateral subsequent challenge with the TS/A parental cells on day 28. The ALVAC-IL12 treatment is not effective in nude mice, suggesting the critical role of T cells. CD4 and CD8 T cells infiltrated the tumors treated with ALVAC-IL12 in the BALB/c model. Furthermore, in vivo depletion of CD4+ T cells totally abrogated the induction of the long-term antitumoral immune response by ALVAC-IL12. Interestingly, some tumor growth inhibition was also observed with ALVAC-betaGal treatment and a vaccinal effect was found in 33% of the treated animals, suggesting an adjuvant effect of the vector itself. Other ALVAC vectors expressing murine cytokines (IL-2, GM-CSF, IFN-gamma) were evaluated in the same model. Major antitumoral activity was observed with ALVAC-GM-CSF. However, a combination of ALVAC-GM-CSF and ALVAC-IL12 had no synergistic effect. These results suggest that in vivo gene transfer with canarypox virus expressing IL-12 may provide an effective and safe strategy for the treatment of human cancers.

Antitumor activity of bax and p53 naked gene transfer in lung cancer: in vitro and in vivo analysis.

In vitro and in vivo data have demonstrated that virus-mediated p53 gene transfer can induce active cell death and lung tumor regression. In contrast, the therapeutic potential of bax, another apoptosis-inducing gene, has not been described. We compared p53 and bax cytotoxic effects by transient transfection of an average of 25 +/- 5% of the H-322 and H-358 bronchioloalveolar carcinoma cell lines in vitro. Under these conditions, bax expression killed 70 to 90% of the transfected cells whereas p53 killed only 40% of them. The killing activity of both genes involved apoptosis, as shown by TUNEL staining. Surprisingly, BrdU incorporation indicated that the cells that did resist Bax toxicity were blocked in the pre-S phase of the cell cycle, a result expected for p53 only. In vivo, repeated injections of naked DNA encoding Bax or p53 inhibited the growth of 4-mm preestablished H-322 tumors in nude mice. Growth retardation only, and not inhibition, was observed in H-358, a poorly transfectable and rapidly growing tumor. These results indicate that Bax and p53 share a similar, strong antitumor activity in vivo, even if the former is a more potent inducer of apoptosis in vitro.

Management of pediatric non-Hodgkin's lymphoma.

Over the past 15 years, significant progress has been made in the understanding of the molecular mechanism involved in malignant transformation of lymphocytes as well as in the management and treatment of non-Hodgkin's lymphoma (NHL) in childhood. Cyto-histological classifications and immunophenotyping of different types of NHL have contributed to the characterisation of three major subtypes of NHL in children i.e. Burkitt's lymphoma (BL), lymphoblastic lymphoma (LL) and large cell lymphoma (LCL). Precise staging of the disease at diagnosis is necessary before the onset of the treatment and should be performed as quickly as possible. Presence of bone marrow and central nervous system (CNS) involvement are major prognosis criteria. In most cases, surgery has no therapeutic role and is required only for diagnostic procedures. Similarly, several studies have demonstrated that irradiation of various sites including the CNS does not improve survival. Thus, NHL patients are usually treated with chemotherapy alone. BL and LL have distinct clinical presentations and require completely different chemotherapy protocols. After comparable induction phases with intensive chemotherapy regimens, the former is usually treated with a short consolidation phase while the latter receives a long lasting consolidation consisting of intermittent chemotherapy for at least one year. The prognosis of stage I-II, and III-IV bone marrow negative NHL of children is excellent with respectively 95% and 75% long term survival. However, patients with concomittent CNS and bone marrow involvement in both histological subtypes have a considerably worse prognosis with only 30% long term survival.(ABSTRACT TRUNCATED AT 250 WORDS)

A phase-II study of adoptive immunotherapy with continuous infusion of interleukin-2 in children with advanced neuroblastoma. A report on 11 cases.

Nine children with poor prognosis neuroblastoma have been treated by continuous infusion of IL-2 and autologous LAK cells, as described previously by West et al. in adult patients. Six patients were in relapse after high-dose chemotherapy and autologous BMT and three presented with primary refractory disease after conventional therapy. Although patients were very young (median age 6 years; average weight 17 kg), infusion of IL-2, cytapheresis and reinjection of LAK cells appeared feasible with the usual and transient complications observed with IL-2. Haematological toxicity, although reversible, was more important than usually described and due to the presence of bone-marrow metastases in 8 of the 9 patients. Life-threatening toxicity was observed in only one of the admission centres and was probably due to the rapid reinjection of a very large number of activated cells. Two patients presenting with very active disease after high-dose chemotherapy and autologous or allogeneic BMT received IL-2 alone, at 120 days and at 90 days after the graft. The reactivation of grade-II GVHD was the major complication in the patient treated after an allograft, whereas no BMT-related toxicity was observed in the patient treated after the autologous BMT. Immunological modifications induced by IL-2 were very different between these patients. As expected, a preferential outgrowth of NK cells with both NK and LAK activity was observed in the patient treated just after the autograft. In contrast, in the patient treated after an allograft and in the 9 patients in relapse, T lymphocytes remained the major mononuclear cell population with a very large excess of CD8+ T cells. All patients progressed after the first induction cycle with the exception of the only patient treated after autologous BMT who reached a very good partial remission with disappearance of the local tumor and bone metastases. Although very preliminary, these data clearly show that the efficacy of IL-2 largely depends on the patient's immunological status with the optimal effect being observed when IL-2 is given in the first few months following an autograft.