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Human natural killer (NK) cells are potent effectors involved in destruction of virus infected cells and tumours. Their cytolytic function is regulated by surface receptors that either inhibit or increase the NK-mediated cytotoxicity. Under physiological conditions, NK cells recognize major histocompatibility complex (MHC)-class I molecules through surface receptors delivering signals that inhibit NK cells function. Nonetheless, the "missing self hypothesis", i.e. the release of an inhibitory signal by the interaction between HLA I-specific inhibitory receptors and their ligands, is not sufficient to entirely explain the regulation of NK cytotoxicity. Activating and co-receptors also play a central role in NK cell activation. In the haematology field, several lines of evidence suggest that NKs participate to the anti-leukaemia immune response: (1) leukaemic cells have down-regulated HLA-class I molecule expression and putative allele loss, (2) several reports have indicated an inverse relationship between NK cell number or activity and prognosis in acute leukaemia, (3) NK-cell activity dependent immunodeficiency syndromes are associated with an increased frequency of lymphoid haematological malignancies, (4) recent data support a role for NK cells in the graft-versus-leukaemia effect observed in allogeneic bone marrow transplantation. All these data raise several questions. How NK cells kill leukaemic targets, and how can leukaemia escape from innate immunity surveillance? What are the therapeutic possibilities to manipulate NK receptor-ligand interaction in order to increase leukaemia cell destruction? The responses to these questions will contribute to immunotherapy advancements in leukaemia and more generally in cancer.

The study presented is a clinical and economic comparison of bone marrow (BM) and blood cells (BC) allogeneic transplantation. We performed a case-control study to compare 17 patients receiving allogeneic BC transplant in a pilot study to an historical group of 17 patients allografted with BM. We evaluated the clinical outcomes and the direct medical costs of transplantation from conditioning regimen until day 100 by detailed observation of patients' medical records. Patients in the BC group received a median of 8 x 10(6)/kg CD34+ cells (1.58-29.1) and 266 x 10(6)/kg CD3+ cells (128-469). All patients had neutrophil engraftment with a median of 14 days in the BC group vs 19 days in the BM group (P < 0.05). The Kaplan-Meier estimation of the median number of days to a platelet count of > 25 x 10(9)/l, independent of platelet transfusion, was significantly shorter in the BC group (15 (9-74)) compared with the BM group (25 (15-45)). Acute graft-versus-host disease (AGVHD) of grade > or = 2 was not significantly different between the two groups. Patients treated with BC presented a US$16,134 decrease in the cost of the first 100 days (29%, P = 0.006). Our comparison suggested that platelet reconstitution and total costs were in favor of the BC group.

Dose-effect relationships of high-dose melphalan were evaluated in 37 patients with measurable relapsed or refractory acute leukemias. Thirteen patients (Group 1) received 70-100 mg/m2 of melphalan without marrow rescue and 24 patients (Group 2) received 140-180 mg/m2 of melphalan followed by marrow transplantation. Patients in both groups were comparable with respect to age, sex, diagnosis, and status of the leukemia. The complete remission rate was 23% in Group 1 versus 75% in Group 2 (P less than 0.01). Hematological recovery of remission patients was not statistically different in either group. Nonhematological toxicity was comparable in the two dose ranges examined. These results demonstrate the existence of a dose-response effect of high-dose melphalan regimens in relapsed acute leukemias, without marked increases in nonhematological toxicity with these doses.

Septicaemias are frequent and severe in patients with acute leukaemia under aplastic treatment. The present study concerns 69 such patients: 29 with acute lymphoblastic leukaemia (ALL), and 40 with acute non-lymphoblastic leukaemia (ANLL). All were treated in single rooms in the same hospital and in similar conditions. The overall incidence of septicaemia was 62%; it was 60% in patients with recently diagnosed ALL and 68% during relapses. More than 34% of ALL patients and 82.5% of ANLL patients had one or several episodes of septicaemia. Among the 74 pathogens isolated 50% were Gram-positive organisms, 45% Gram-negative organisms and 5% Candida spp.. The first episodes of septicaemias were predominantly caused by Gram-positive spp. (61%) and the subsequent ones by Gram-negative spp. (60%). The primary infection could only be diagnosed in 19% of the cases and was most frequently located in the digestive tract or perineal region. The most common focal complications were lung infections (18 cases), skin infections (12 cases) and septic shock (15 cases). Seventy-four p. cent of the patients survived with prompt and potent antibiotic therapy. Death occurred in 26% and was clearly related to the following factors: chemotherapy of relapsed leukaemia and/or blastic aplasia and/or successive episodes of septicaemia. The incidence and severity of septicaemias in leukaemic patients will only be reduced by improved prophylactic measures against infection and by less pronounced and shorter chemotherapy-induced granulocytopenia.

Cyclic cytidine 3':5'-monophosphate (cyclic CMP), cyclic guanosine 3':5'-monophosphate (cyclic GMP), and cyclic adenosine 3':5'-monophosphate (cyclic AMP) contents of leukocytes and urines of leukemic patients have been investigated. We have studied four types of leukemia: acute myeloblastic leukemia; chronic myelocytic leukemia; acute lymphoblastic leukemia; and chronic lymphocytic leukemia. As controls, the cyclic nucleotide content of leukocytes and urines of healthy volunteers and patients with solid tumors selected for their normal hemogram has been determined. It has also been measured in phytohemagglutinin-stimulated lymphocytes. Our data show that: (a) the concentration of cyclic CMP is always lower than that of cyclic GMP or cyclic AMP; (b) in urines, the concentrations of the three nucleotides are higher in patients than in healthy volunteers, the greatest differences being observed between the cyclic CMP concentrations of acute leukemia patients and controls; and (c) in white blood cells, cyclic AMP concentration is lower in leukemic than in normal cells. The cyclic GMP concentration is the same everywhere except in monoblastic cells and leukocytes from solid tumor patients. High cyclic CMP levels are associated only with acute leukemia, whether myeloblastic, monoblastic, or lymphoblastic, a fact which suggests that cyclic CMP could be a biochemical marker of hematopoietic stem cell malignancy.

A trial of immunotherapy in the maintenance treatment of non-lymphoblastic acute leukaemias led to a comparison of 2 groups of patients in complete remission. Group C (14 patients) received only monthly reinduction chemotherapy. Group C + I (17 patients) received identical chemotherapy together with weekly immunotherapy combining BCG and irradiated leukaemic cells. Whilst the duration of the first remission was unmodified, the overall survival and above all survival after the first recurrence were prolonged in group C + I. These results were all the more marked when a homogeneous patients having received the same induction chemotherapy is considered.

Granulocytic progenitor cells (CFC) are a better reflection of stem cell pools than precursors. Their total number can be estimated during hematologic steady-state (N = 70 +/- 29 x 10(5) CFC/kg); the amount of marrow necessary to perform a bone marrow transplantation is only 1% of the total pool. CFC are useful but have a mainly qualitative value in evaluating the viability of marrow stored for 24 h at room temperature (92%) or marrow thawed after DMSO cryopreservation (62%). Sequential study of CFC in patients receiving autologous marrow transplantation enables differentiation of engraftment from autologous recovery. In 11 recipients of autologous marrow transplantation, no statistical relation was observed between number of infused CFC and severity of granulocytopenia. Further studies will be necessary to evaluate a better marker of real hematopoietic stem cells.

Vindesine is a semisynthetic vinca alkaloïd. The short plasma half-life suggested that continuous infusion can improve the therapeutic results by maintaining a constant plasma level. Twenty one patients (acute lymphoblastic leukemia = 5 cases; blastic crisis of chronic myelocytic leukemia = 6 cases; lymphomas 10 cases) received 5-day Vindesine infusion (0,7 mg/m2/d). All these patients had previously several treatments and were resistant to usual chemotherapies including other vinca alkaloids (76% of cases). Eighteen patients were evaluable for response: 13 (72%) had partial responses or minor regressions. Toxicity was not important. Continuous 5-day infusion of Vindesine might be used widely in patients with blood diseases.

Twenty-six children with acute leukemia were treated with allogeneic marrow transplantation from HLA identical siblings after a conditioning regimen with Cyclophosphamide-total body irradiation (19 patients), Melphalan-total body irradiation (6 patients) or Busulfan-cyclophosphamide (1 patient). Eighteen were transplanted in complete remission (4 with acute non lymphoblastic leukemia in first remission, 14 with acute lymphoblastic leukemia: 6 in first, 6 in second and 2 in subsequent remission): 2 died of cytomegalovirus pneumoniae, 1 relapsed and 15 survive in continuous complete remission from 5 to 42 months after transplantation (median = 22 months). Eight were transplanted in relapse, 7 achieve complete remission, 5 of them relapsed, 1 died of G.V.H. and 1 survives in continuous complete remission 46 months after transplantation. Actuarial analysis shows a disease free survival rate at 3 years of 82% for patients transplanted in remission and 12% for patients transplanted in relapse (p less than 0.01).

Seven patients with relapsed acute leukaemia were treated with high-dose melphalan (HDM) followed by the infusion of autologous cryopreserved remission marrow. Toxicity was minimal and all seven patients had a complete response. Four patients are still in unmaintained remission at 14, 13, 10, and 3 months, the first two having received a second course of HDM to consolidate the result. The role of HDM as a form of intensification therapy for patients with acute myeloid leukaemia in first remission should be investigated.