Transcriptional and posttranscriptional regulation of tumor necrosis factor gene expression in human monocytes.

Regulation of tumor necrosis factor (TNF) gene expression was investigated in resting human monocytes and in 12-O-tetradecanoylphorbol-13-acetate (TPA) activated monocytes. TNF transcripts were undetectable in resting monocytes. However, in TPA-activated monocytes, TNF mRNA was first detectable by 3 h and reached maximal levels by 12 h of drug exposure. Using run-on transcription assays, the TNF gene was transcriptionally inactive in resting monocytes, but was rapidly activated after TPA exposure. The protein synthesis inhibitor, cycloheximide (CHX), had no detectable effect on levels of TNF transcripts in resting monocytes, while this agent superinduced the level of TNF mRNA by 50-fold in TPA-activated cells. TPA activated monocytes were also exposed to actinomycin D and/or CHX to determine whether transcriptional or posttranscriptional control of TNF gene expression was responsible for the induction of TNF transcripts. After 1 h of actinomycin D treatment, the amount of TNF transcripts was reduced by 75%. In contrast, no difference in TNF mRNA levels was observed in TPA-activated monocytes exposed to CHX alone or CHX in combination with actinomycin D. These findings indicated that CHX prevented the degradation of TNF mRNA by inhibiting the synthesis of a labile protein. Run-on transcription assays performed on cells exposed to either TPA or the combination of TPA and CHX further indicated that CHX treatment increased transcription of the TNF gene. Thus, TNF gene expression is controlled at the transcriptional level in resting human monocytes, while both transcriptional and posttranscriptional events regulate the level of TNF transcripts in TPA-activated cells.

Tumor necrosis factor expression in human epithelial tumor cell lines.

Tumor necrosis factor (TNF) is a monokine with in vitro cytotoxicity for some but not all tumor cells. The basis for sensitivity and resistance to the antitumor effects of this agent remains unclear. The present studies have monitored the effects of TNF on 14 epithelial tumor cell lines. Eleven of these cell lines were resistant to the growth inhibitory effects of TNF (50% inhibitory concentration greater than 1,000 U/ml). 12 of the 14 tumor cell lines has detectable levels of high affinity cell surface TNF binding sites, thus suggesting that resistance was not often due to the absence of cell surface TNF receptors. Northern blot analysis demonstrated that three of the eleven resistant cell lines expressed detectable levels of TNF mRNA. Furthermore, both sensitive and resistant epithelial tumor cells had the capacity to express TNF transcripts in the presence of the protein synthesis inhibitor, cycloheximide. Finally, the presence of TNF expression at the RNA level is shown to be associated with the production of a TNF-like protein in the resistant Ov-D ovarian carcinoma cells. These findings suggest that certain human epithelial tumor cell lines inherently resistant to TNF also express this cytokine.

Expression of platelet-derived growth factor (PDGF)-related transcripts and synthesis of biologically active PDGF-like proteins by human malignant epithelial cell lines.

Human malignant epithelial cell lines were analyzed for expression of platelet-derived growth factor (PDGF) genes. Of the 12 cell lines tested, 9, derived from breast, lung, gastric, and ovarian carcinomas, were found to express both PDGF-1 and PDGF-2 genes. The levels of both PDGF-1 and PDGF-2 transcripts were superinduced when these cells were treated with cycloheximide, an inhibitor of protein synthesis. These cells also released an activity that in studies with BALB-c/3T3 cells, inhibited binding of 125I-labeled PDGF and stimulated incorporation of [3H]thymidine. This stimulating activity was inhibited after reduction of the conditioned media by mercaptoethanol or after preincubation with antibodies to PDGF. Moreover, this activity was not affected by heat treatment. Immunoprecipitation studies revealed that breast, lung, and gastric carcinoma cells produced PDGF-like proteins that migrated as 30- and 32-kD species under nonreducing conditions and as 15- and 16-kD species under reducing conditions. In contrast, malignant cells of ovarian origin produced 14-16-kD PDGF-like proteins that were unchanged in mobility after reduction. As PDGF receptors were not detected on these malignant epithelial cells, the production of PDGF-like proteins may affect other cells in the microenvironment by paracrine mechanisms and may contribute to excessive cell proliferation, inflammatory reactions, and connective tissue remodeling seen in certain carcinomas.

Transcriptional and posttranscriptional control of c-fos gene expression in human monocytes.

We examined the mechanisms that are responsible for the regulation of c-fos gene expression in human monocytes. Levels of c-fos mRNA were low or undetectable in resting monocytes. Results of run-on transcription assays, however, demonstrated that both the first two and last two exons of the c-fos gene were transcribed at similar rates, and that only the sense strand of this gene was transcribed. These findings suggest that the level of c-fos transcripts in resting human monocytes is controlled at a posttranscriptional level. Activation of resting monocytes with phorbol ester was associated with a rapid and transient increase in c-fos mRNA levels. This increase in c-fos transcripts was related to an enhanced rate of c-fos transcription. Moreover, exposure of resting monocytes to inhibitors of protein synthesis induced (i) a rapid and marked (300-fold) increase in c-fos mRNA levels, despite only a 9-fold increase in c-fos transcription, and (ii) a prolongation of the half-life of c-fos mRNA. Thus, while posttranscriptional control was responsible for the down-regulation of c-fos transcripts in both resting and activated human monocytes, transcriptional mechanisms were responsible for the transient increase in c-fos expression induced by phorbol ester. Furthermore, the marked increases in c-fos mRNA associated with inhibition of protein synthesis were regulated by both transcriptional and posttranscriptional mechanisms. These findings may be related to recent observations which indicate that both positive and negative factors transcriptionally regulate c-fos gene expression and that sequences found in the 3'-untranslated region of the c-fos mRNA are responsible for the stability of this transcript.

Transcriptional and posttranscriptional regulation of CSF-1 gene expression in human monocytes.

Regulation of CSF-1 gene expression was investigated in human monocytes. CSF-1 transcripts were at low or undetectable levels in resting monocytes. However, in monocytes treated with 12-O-tetradecanoylphorbol-13-acetate (TPA), CSF-1 mRNA was increased by 3 h and reached maximal levels by 12 h of drug exposure. When nuclear run-on assays were used, CSF-1 gene transcription was also at low or undetectable levels in resting monocytes but was activated after TPA exposure. TPA-treated monocytes exposed to actinomycin D further demonstrated that the half-life of the CSF-1 mRNA is 0.9 h. The results also demonstrated that the protein synthesis inhibitor, cycloheximide (CHX), increases CSF-1 mRNA levels in both resting and TPA-treated monocytes. These effects of CHX occurred in the absence of detectable increases in CSF-1 gene transcription. Moreover, treatment of monocytes with CHX and actinomycin D demonstrated that inhibition of protein synthesis is associated with stabilization of the CSF-1 transcript. Taken together, these findings indicated that CSF-1 gene expression is controlled at both transcriptional and posttranscriptional levels in human monocytes.

Interrelationships of protein and DNA syntheses during replication of mammalian cells.

During the replication of chromatin, the syntheses of the histone protein and DNA components are closely coordinated but not totally linked. The interrelationships of total protein synthesis, histone protein synthesis, DNA synthesis, and mRNA levels have been investigated in Chinese hamster ovary cells subjected to several different types of inhibitors in several different temporal combinations. The results from these studies and results reported elsewhere can be brought together into a consistent framework which combines the idea of autoregulation of histone biosynthesis as originally proposed by W. B. Butler and G. C. Mueller (Biochim. Biophys. Acta 294:481-496, 1973] with the presence of basal histone synthesis and the effects of protein synthesis on DNA synthesis. The proposed framework obviates the difficulties of Butler and Mueller's model and may have wider application in understanding the control of cell growth.

Standard-risk medulloblastoma treated by adjuvant chemotherapy followed by reduced-dose craniospinal radiation therapy: a French Society of Pediatric Oncology Study.

OBJECTIVE: The primary objective of this study was to decrease the late effects of prophylactic radiation without reducing survival in standard-risk childhood medulloblastoma. PATIENTS AND METHODS: Inclusion criteria were as follows: children between the ages of 3 and 18 years with total or subtotal tumor resection, no metastasis, and negative postoperative lumbar puncture CSF cytology. Two courses of eight drugs in 1 day followed by two courses of etoposide plus carboplatin (500 and 800 mg/m(2) per course, respectively) were administered after surgery. Radiation therapy had to begin 90 days after surgery. Delivered doses were 55 Gy to the posterior fossa and 25 Gy to the brain and spinal canal. RESULTS: Between November 1991 and June 1998, 136 patients (median age, 8 years; median follow-up, 6.5 years) were included. The overall survival rate and 5-year recurrence-free survival rate were 73.8% +/- 7.6% and 64.8% +/- 8.1%, respectively. Radiologic review showed that 4% of patients were wrongly included. Review of radiotherapy technical files demonstrated a correlation between the presence of a major protocol deviation and treatment failure. The 5-year recurrence-free survival rate of patients included in this study with all optimal quality controls of histology, radiology, and radiotherapy was 71.8% +/- 10.5%. In terms of sequelae, 31% of patients required growth hormone replacement therapy and 25% required special schooling. CONCLUSION: Reduced-dose craniospinal radiation therapy can be proposed in standard-risk medulloblastoma provided staging and radiation therapy are performed under optimal conditions.

Treatment of high risk medulloblastomas in children above the age of 3 years: a SFOP study.

AIM: Improvement of EFS of children older than 3 years with high risk medulloblastoma. METHODS: Between 1993 and 1999, 115 patients (3-18 years, mean 8 years) with high risk medulloblastoma were included. After surgery treatment consisted of chemotherapy ('8in1' and etoposide/carboplatin) before and after craniospinal radiotherapy. RESULTS: Patients were staged using Chang-criteria (PF residue only, M1 and M2/M3) by local investigator as well as by central review panel (82.4% concordance). Chemotherapy was well tolerated without major delays in radiotherapy. With a mean follow up of 81 months (9-119), 5-year EFS was 49.8% and OS 60.1%. In detail according to subgroups EFS was 68.8% for PF residue only, 58.8% for M1 disease and 43.1% for M2/M3. CONCLUSION: M1 patients are legitimate high risk patients. Survival rates are still very low for high risk medulloblastoma patients and future trials should therefore focus on more intensive (chemotherapy/radiotherapy) treatment.

Expression of the platelet-derived growth factor 1 and 2 genes in human myeloid cell lines and monocytes.

Platelet-derived growth factor (PDGF), a potent mitogen for mesenchymal cells, consists of PDGF-1 and PDGF-2 polypeptide chains which are linked by disulfide bonds. Sequence analysis has revealed that: (a) the PDGF-2 chain is encoded by the c-sis protooncogene, the cellular counterpart of the simian sarcoma viral oncogene; (b) the PDGF-1 and PDGF-2 chains are related; and (c) the PDGF-1 gene has no known viral homologue. We have previously shown that the PDGF-2 gene is expressed during 12-O-tetradecanoylphorbol-13-acetate (TPA) induced monocytic differentiation of human HL-60 leukemia cells. In the present study, PDGF-1 and PDGF-2 gene expression was compared in HL-60 cells, human THP-1 monocytic leukemia cells, and human monocytes. Uninduced HL-60 cells, uninduced THP-1 cells, and resting monocytes had no detectable PDGF-1 or PDGF-2 mRNA. In contrast, both PDGF-1 and PDGF-2 transcripts were detected in HL-60 cells and monocytes induced with TPA, while only PDGF-1 mRNA was found in TPA-treated THP-1 cells. Moreover, neither of these transcripts were found during drug induced granulocytic differentiation of HL-60 cells. Cycloheximide, an inhibitor of protein synthesis: (a) failed to increase PDGF-1 and PDGF-2 mRNA levels in uninduced HL-60 cells; (b) increased PDGF-2, but not PDGF-1, mRNA in resting monocytes; and (c) increased levels of PDGF-1 and PDGF-2 mRNA in HL-60 cells and monocytes treated with TPA. This effect of cycloheximide was related in part to stabilization of both transcripts. Thus, PDGF-1 and PDGF-2 genes are differentially regulated in myeloid cells, although they share common control mechanisms at the post-transcriptional level. Differential regulation of PDGF gene expression would result in altered chain composition of the PDGF protein and possibly changes in biological activity.

Effects of carbamoylation on cell survival and DNA repair in normal human embryo cells (IMR-90) treated with various 1-(2-chloroethyl)-1-nitrosoureas.

The possibility was examined that the carbamoylating activity of some chloroethylnitrosoureas could interfere with the activity of normal human cells to survive treatment with these drugs; 1-(2-chloroethyl)-3-(trans-4-hydroxycyclohexyl)-1-nitrosourea, which has strong carbamoylating activity, inhibited the rejoining of drug or X-ray-induced DNA strand breaks in IMR-90 cells, whereas the noncarbamoylating cis-2-hydroxy isomer had little or no effect; 1-(2-chloroethyl)-3-(trans-4-hydroxycyclohexyl)-1-nitrosourea was twice as potent as the cis-2-hydroxy isomer in reducing colony survival. The moderate or high carbamoylating drugs 1,3-bis(2-chloroethyl)-1-nitrosourea and 1-(2-chloroethyl)-3-(cyclohexyl)-1-nitrosourea had effects resembling those of 1-(2-chloroethyl)-3-(trans-4-hydroxycyclohexyl)-1-nitrosourea. The low carbamoylating drug 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)-1-nitrosourea had effects resembling those of the cis-2-hydroxy isomer. 1-(2-chloroethyl)-1-nitrosourea, although a strong carbamoylator in chemical systems, behaved biologically as if it were a low carbamoylator. This can be rationalized on the basis of limited cellular uptake of cyanate ion. The results suggest that carbamoylation may inhibit the nucleotide excision repair of chloroethylnitrosourea-induced DNA damage that may be crucial to the ability of normal human cells to recover from the action of these drugs. Previous work has indicated that susceptible human tumor cells are sensitive to chloroethylnitrosoureas because of a lack of a DNA repair protein (guanine O6-alkyltransferase) that is not involved in nucleotide excision repair. On the basis of these findings and other evidence, further clinical trials of appropriate noncarbamoylating chloroethylnitrosoureas would be justified.

Constitutive production of platelet-derived growth factor-like proteins by human prostate carcinoma cell lines.

Prostate carcinoma cell lines DU-145 and PC-3 express both platelet derived growth factor (PDGF)-1 and PDGF-2/sis genes. Concomitantly, these cells synthesize and secrete PDGF-like proteins, as judged by indirect immunofluorescence and by direct immunoprecipitation with specific PDGF antiserum. Conditioned media derived from DU-145 and PC-3 cells stimulated the incorporation of [3H]thymidine by 3T3 cells and competed with 125I-labeled PDGF for its binding to cell surface receptors of 3T3 cells. The biological activity was stable to heating at 100 degrees C for 10 min, sensitive to reducing agents, and neutralized by the IgG fraction of PDGF antiserum, properties similar to those of authentic PDGF. Both DU-145 and PC-3 cell lines appear to lack receptors for PDGF as indicated by their inability to mitogenically respond to PDGF and receptor binding of 125I-labeled PDGF. Production of PDGF-like proteins by human prostate carcinoma cells may play an important role in a paracrine mode in the organization of the extracellular matrix of the malignant tissue.

DNA cross-linking responses of human malignant glioma cell strains to chloroethylnitrosoureas, cisplatin, and diaziquone.

Cell strains derived by culture of malignant glioma (astrocytoma grade III-IV) surgical specimens were tested for the production of DNA interstrand cross-links (ISC) and DNA-protein cross-links following treatment in vitro with 1-(2-chloroethyl)-1-nitrosourea, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine), 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)-1-nitrosourea (PCNU), cis-dichlorodiammineplatinum(II) (cisplatin), and 3,6-diaziridinyl-2,5-bis(carboethoxyamino)-1,4-benzoquinone (diaziquone). ISC and DNA-protein crosslinks were measured by means of the DNA alkaline elution technique. Large differences among the cell strains were observed in DNA cross-linking responses to individual agents. The DNA responses to the chloroethylnitrosoureas, cisplatin, and diaziquone were largely independent of each other, except for a weak correlation between ISC responses to chloroethylnitrosoureas were distributed bimodally, in accord with a phenotypic distinction between Mer+ and Mer- cells. ISC responses to cisplatin and diaziquone showed significant variation among cell strains, but the distributions were not bimodal. The results demonstrate the existence of diverse DNA cross-linking response patterns among cell strains from different tumors of a given histological type.

Synthesis of PDGF by cultured human T cells transformed with HTLV-I and II.

Human T cells immortalized by human T lymphotropic virus (HTLV)-I and HTLV-II express the genes encoding both chains of platelet-derived growth factor (PDGF). These cells produce biologically active PDGF-like molecules of 31 and 32 kD, identified in the conditioned media of the virus-infected cells by direct immunoprecipitation, under non-reducing conditions, with antisera to PDGF. Upon reduction, the PDGF-like molecules are converted to mitogenically inactive single chains of 14 and 15 kD. The HTLV-transformed cells produce PDGF-like molecules regardless of their ability to produce viral particles. No PDGF-related mRNAs, PDGF-like proteins, nor PDGF-like mitogenic activity were detected in normal human T cells stimulated by phytohemagglutinin or in a T cell line which is not infected by HTLV. It is possible that one of the pathways of immortalization of T cells by HTLV-I or II might be by activation of PDGF-related genes.

Central nervous system involvement in American Burkitt's lymphoma.

Sixty-four patients with American Burkitt's lymphoma (AMBL) treated at the National Cancer Institute were reviewed to determine the frequency and characteristics of central nervous system (CNS) involvement. Patients with minimal or completely resected tumor never had CNS disease. Of the 45 patients with more extensive disease, 15 had CNS disease: nine presented with CNS disease, six of whom subsequently had recurrent CNS disease, and six developed CNS disease only at relapse. There was a significant association between CNS and bone-marrow disease at presentation. Therapy of CNS disease consisted of short courses of intrathecal chemotherapy with cytosine arabinoside and methotrexate. Cranial irradiation was given only to patients with CNS relapse. There are six long-term survivors (LTS) who have been disease free for four to six years post chemotherapy. Of these six LTS, three presented with CNS disease, two experienced isolated CNS relapse, and one had CNS disease both at presentation and at relapse. Three of the six LTS never received cranial irradiation. It is concluded that CNS involvement in AMBL can be effectively treated, and that long-term remission, which is probably cure, can be achieved.

Etoposide and carboplatin in neuroblastoma: a French Society of Pediatric Oncology phase II study.

PURPOSE: A phase II study of etoposide (VP 16) and carboplatin (CBDCA) was performed in patients with metastatic neuroblastoma (NB). The aim of the study was to find an alternative treatment for induction with different toxicities than the VP 16/cisplatin (CDDP) combination. PATIENTS AND METHODS: Forty-seven patients who were from 6 months to 16 years of age, with either relapsed (29) or primary resistant (18) NB, were included in a cooperative multicenter phase II study of the French Society of Pediatric Oncology (SFOP). The schedule consisted of 5 consecutive days of VP 16 100 mg/m2/d and CBDCA 160 mg/m2/d. RESULTS: The response rate for the 39 assessable patients was 43%; there were four complete remissions and 13 partial remissions. Neither the status of the patients nor the total dose of CDDP that was received previously influenced response. Hematologic toxicity was marked and caused considerable delay between courses (median interval, 39 days). In these heavily pretreated patients, 16% had a more than 50% decrease in creatinine clearance and a 22% World Health Organization (WHO) grade 2 ototoxicity. CONCLUSION: This VP 16/CBDCA combination deserves further evaluation for efficacy and toxicity in newly diagnosed patients, and the combination of both drugs should be considered for high-dose therapy with bone marrow transplantation.

Natural killer (NK) cells inhibit human umbilical cord blood erythropoiesis.

To examine the role of NK cells on in vitro human umbilical cord (HUC) blood erythropoietic progenitor growth, 25 normal HUC blood samples were depleted of CD56+ cells by using immunomagnetic beads coated with CD56 monoclonal antibodies (mAb). When stimulated by erythropoietin (Epo) to form colonies in plasma clot medium, the CD(56+)-depleted preparations demonstrated a two-fold increase in the number of early erythropoietic progenitors (BFU-E) over nondepleted preparations. This stimulatory effect of CD56+ depletion on BFU-E growth was not due to artifactual stimulations of other accessory cells by the mAb or the dynabeads used in the depletion procedure, since separate addition of these materials to culture did not exert any stimulatory effect on BFU-E growth. Direct co-culture of purified NK and autologous cord blood mononuclear cells (MNC) in plasma clot medium resulted in a dose-dependent decrease in BFU-E population. In addition, when NK and MNC were cocultured separately in double-layer cultures, the expansion of BFU-E was significantly decreased. Because direct cell-to-cell contact is prohibited in double-layer cultures, the observed inhibition of BFU-E proliferation could be mediated at least in part through soluble factors. To test this hypothesis, NK cell supernatant fluid obtained 24 hours after NK cell incubation was added to plasma clot culture medium. A significant decrease in BFU-E number was again observed. In conclusion, our results indicate that HUC blood BFU-E proliferation is inhibited by NK cells, and that the mechanism of this inhibition is mediated, at least in part, by one or more humoral factors.

Ifosfamide and etoposide in childhood osteosarcoma. A phase II study of the French Society of Paediatric Oncology.

The aim of this phase II study was to determine the efficacy of high-dose ifosfamide with moderate dose etoposide in childhood osteosarcoma. From January 1992 to January 1995, 27 children (15 male, 12 female) with relapsed or refractory evaluable osteosarcoma were included in a phase II study of two courses of ifosfamide 3g/m2/day and etoposide 75 mg/m2/day for 4 days. Median age was 14 years (7-19 years). All but one had received high-dose methotrexate and doxorubicin as first-line treatment. 22 patients had previously received ifosfamide. This regimen was given as first-line in 1 patient, second-line in 23 and third-line in 3. Evaluable disease was lung metastases in 21 patients, local relapse in 5 and adenopathy in 1. There were six complete responses, seven partial responses, three minor responses, six stable disease and five progressive disease (including one mixed response). Response rate was 48% (95% confidence interval, 29-67%). Duration of response was not available (10 responding patients had other treatments). Response rate was equivalent in the subgroup of 22 patients who had previously received ifosfamide (4 CR, 6 PR). Among 3 patients who received the phase II regimen as third-line chemotherapy, there was 1 PR. All but 4 patients had a well tolerated grade 4 neutropenia. Transient mild confusion or seizures were each observed once. 5 patients are alive 15-31 months after the beginning of chemotherapy. This combination of drugs at this dosage has tolerable toxicity, is efficient and deserves evaluation in phase III studies.

Carboplatin before and during radiation therapy for the treatment of malignant brain stem tumours: a study by the Société Française d'Oncologie Pédiatrique.

Childhood malignant brain stem tumours have a very poor prognosis with a median survival of 9 months despite radiotherapy. No chemotherapy has improved survival. However, carboplatin has been reported to have activity in glial tumours as well as antitumour synergy with radiation. Our aims were to test the response rate of these tumours to carboplatin alone and to evaluate the efficacy on survival of carboplatin alone followed by concurrent carboplatin and radiotherapy. Patients younger than 16 years with typical clinical and radiological presentation of infiltrating brain stem tumour, as well as histologically-documented cases in the atypical forms, were eligible. Two courses of carboplatin (1050 mg/m2 over 3 days) were administered initially. This treatment was followed by a chemoradiotherapy phase including five weekly carboplatin courses (200 mg/m2) and conventional radiotherapy. 38 eligible patients were included. No tumour response was observed after the initial phase. This schedule of first-line carboplatin followed by concurrent carboplatin and radiotherapy did not improve survival.

Bone marrow transplantation in sickle cell disease: the Belgian experience.

Twenty eight patients underwent bone marrow transplantation (BMT) for sickle cell anemia in Belgium. The patients were originating from Central Africa, were young and symptomatic. Engraftment occurred in all patients and was sustained in 25. In 3 patients, a bone marrow rejection was observed. One of these patients underwent a second BMT and had an uneventful recovery. One patient died 3 months after BMT of graft-versus-host disease (GVHD). Twenty seven patients are alive and 25 are free of vaso-occlusive related manifestations with a follow-up ranging from 4 to 78 months. So far, eight patients went back to Africa and continue to do well.

Complete remission following donor leukocyte infusion in ALL relapsing after haploidentical bone marrow transplantation.

A 7-month-old boy with a high risk ALL harbouring the translocation (4;11) was grafted with an haploidentical bone marrow from paternal origin. At time of relapse, 11 months after BMT, he received donor leukocyte infusions (DLI) which put him in second CR. GVHD and pancytopenia occurred 2 weeks after DLI and were fully reversed with CsA + prednisolone. Six months later, the child continues to be in second CR, off steroid therapy, without any signs of GVHD. Our limited experience indicates that a second CR can be obtained with acceptable toxicity by DLI in very high risk ALL children who have been previously grafted with haploidentical bone marrow cells.