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The immunomagnetic depletion method for removing tumor cells from bone marrow, previously refined using a Burkitt lymphoma model, was tested with neuroblastoma cells. The efficiency of depletion was quantified by immunofluorescence with a detection limit of 3.3 log of cell depletion corresponding to the elimination of 99.84% of an initial tumor cell content of 10%. A panel of five monoclonal antibodies (UJ13A; UJ127.11; UJ181.4; alpha-Thy1; H11) purged 2.8 log of SKNBE and LAN-1 cells, while two of these antibodies as single agents allowed only for a 1.7 log (UJ13A) and a 1.7 to 2.0 log (alpha-Thy1) depletion. This underlines the advantage of an antibody panel for neuroblastoma purging. The new antibody S-L 11.14, an IgG2a against small cell lung cancer which recognizes 90% of neuroblastoma cells purged 2.8 log.

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.

Twenty-five patients with renal cell carcinoma were treated with continuous infusion of IL-2 (3 x 10(6) units/m2/day) with or without lymphokine-activated killer (LAK) cells; 5 responded to therapy. Functional and immunophenotypic modifications of the peripheral blood lymphocytes (PBLs) did not predict response to therapy. Systemic administration of interleukin-2 (IL-2) during 5 days caused a preferential proliferation of natural killer (NK) cells, although CD4+ T cells remained the predominant circulating population, in particular in three of the five responding patients. The IL-2 low-affinity receptor was induced only on CD4+ T cells. B cells did not proliferate and immunoglobulin levels were not modified by IL-2. In the peripheral blood, the NK function increased but the LAK function in vivo remained low. The T-cell proliferative response in mixed lymphocyte cultures (MLCs) decreased after therapy. Four days of ex vivo culture of PBLs with IL-2 did not modify T and NK distributions, but increased the coexpression of CD8 on NK cells and NKH1 density; it decreased the coexpression of CD16 and induced LAK cell function. Three weeks after the end of the first course of therapy and before the second course was started, all immunological parameters returned to baseline levels, except the T-cell proliferative response in MLCs. The second course of IL-2 therapy induced the same modifications as the first one, with the exception of a higher CD4+ T-cell proliferation.

On leukopheresis products obtained from patients included in a protocol interleukin-2/lymphokine-activated killer (IL-2/LAK) cell therapy, we analyzed, in parallel with the standard culture and on large volumes of these products, different parameters which could either improve LAK cell enhancement or simplify the procedure. We demonstrated first that purification of the mononuclear cells from the leukopheresis product before its culture is not required. An excess of red blood cells and granulocytes (up to 50%) in nonpurified samples improved both the mononuclear cell recovery in short-term culture (4 days) and the activation of LAK cells when the total nuclear cell concentration did not exceed 3 X 10(6)/ml. Different factors can contribute to this enhancing effect: the presence of red blood cells, the liberation of cytokines by granulocytes, or the loss of a population of activated lymphocytes, with liberation of cytokines by granulocytes, or the loss of a population of activated lymphocytes, with larger size and density than resting lymphocytes, during the separation. Supplementation of the medium with 2% heat-inactivated autologous plasma obtained before any treatment rather than with 2% pooled human AB serum does not modify the mononuclear cell recovery in 4-day culture, but it does enhance LAK activity. The inhibitory effect of heat-inactivated autologous plasma on proliferation and activation of LAK cells was never observed, suggesting the absence of suppressive factors in the plasma of the 23 analyzed patients. Similarly, autologous plasma did not modify natural killer and LAK cell functions when added during the cytotoxic assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Very long delay to engraftment (or non-engraftment) was observed in eight patients presenting common immunological features, i.e. excess of blood and bone marrow lymphocytes coexpressing CD8 and CD57 (HNK1) antigens. They were therefore treated by CD8 immunotherapy. Such treatment induced a complete clearance of CD8+, CD57+ cells from the blood and bone marrow in five cases, a partial clearance in one, the absence of clearance in one and a modulation in the last case. No toxic side effects were observed. Platelet recovery was observed in only two patients, but long-lasting granulocyte recovery was seen in six of the cases from day 6 to day 30 after the beginning of CD8 infusion (median = 17 days).

Forty-seven patients with renal carcinoma were included in first line or rescue protocols of immunotherapy including IL2 alone or in association with LAK cells, INF alpha or TNF. The toxicity was mild and the mortality was 2% (1 patient). The response rate was 26%. Nineteen children with neuroblastoma received IL2 either alone or in combination with LAK cells. The morbidity and mortality were higher in patients with end stage disease who had previously received high dose and prolonged chemotherapy. In contrast, the toxicity was mild and transient in patients treated in the months following autologous bone marrow transplantation. The only complete response observed was in 1 child treated with IL2, 4 months after high dose chemotherapy and ABMT. Immunological analysis showed that the immunomodulatory effect of IL2 is very different depending on whether IL2 is used alone or in combination with other cytokines; moreover, the biological effect of IL2 is dependent on the immunological status of the patients prior to IL2 therapy.

Immunological analysis is complementary of morphological analyses in the detection of neuroblastoma BM metastases. It attests the neuroblastic nature of rare pseudolymphocytic isolated cells. The combination of immunocytochemical technique (alkaline phosphate) and double-immunofluorescence technique allows the detection of as few as 10(-5) residual neuroblastoma cells. At the time of bone marrow harvest, it permits a precise evaluation of malignant cells in the graft.

Cytokinins are biological proteins which permit the transmission of signals from one cell to another. These proteins are secreted by groups of specialized cells and are fixed on specific receptors on the surface of responding cells. However, since receptors may be widely distributed, and since the activation of a cell usually permits the release of other cytokinins and a succession of reactions, cytokinins have pleiotropic effects. Cloning of the genes encoding for these cytokinins and their obtention on a large scale by genetic recombination techniques have allowed a better understanding of their biological characteristics and their use in therapy. This cytokinin network is particularly wide in the hematopoietic and in the immune systems. In the present study, we describe the biological properties of the main interleukins and hematopoietic cell growth factors, together with their therapeutic applications, particularly in hemato-oncology.

In 15 patients (11 adults, 4 children) who received IL-2 and LAK cell therapy, we analyzed the different culture conditions which could either improve LAK cell activation and proliferation or which could simplify the procedure. Each parameter was assayed on a large scale and compared to standard culture conditions. Indomethacin had no effects, either positive or negative, on proliferation and activation of the cells. Culturing with 10% AB serum increased proliferation but did not modify total lytic activity compared to 2% AB serum. When cells were cultured in a medium with 2% autologous plasma obtained before any treatment, their proliferation was similar to that obtained in medium supplemented with 2% AB serum but the LAK activity was significantly higher. Autologous plasma obtained at day 8 of treatment (48 h after the first cycle of IL-2 and the day of the first cytapheresis) gave similar results to 2% AB serum. None of the 12 patients showed negative effects suggesting the presence of suppressive factors in the sera. Culturing with autologous plasma in clinical trials will lead to a 25% decrease in the total cost of culture and suppress the risk of viral contamination. Excess of granulocytes in the culture (greater than 30%), if the total nuclear cell concentration did not exceed 3 . 10(6) per ml, induced a better proliferation of mononuclear cells without modification of the activation. These results could be due to the liberation of factors by polynuclear cells, or to the loss during elimination of the granulocytes by the Ficoll separation of cells with similar density supporting LAK activity.

Using experimental modes with normal allogeneic bone marrow (BM) contaminated with Burkitt or neuroblastoma cell lines, and a liquid culture assay, we demonstrated that, when used in optimal conditions, the immunomagnetic depletion technique permitted a reproducible elimination of 3-4 log malignant cells. Results were very similar to those obtained with the complement lysis procedure in Burkitt lymphoma. This immunomagnetic procedure was used in 123 cases of autologous bone marrow transplantation (ABMT) in children with neuroblastoma. The analysis of the cases demonstrated, first, that the procedure induced a significant loss of mononuclear cells but was not toxic for BM precursors. Delays to engraftment observed in a few patients were probably due to the combination of pejorative factors, especially the damage caused to the micro-environment by previous heavy and prolonged chemotherapy or the double ABMT programme. Second, patients presented with profound T-cell defect with undetectable IL2 secretion up to 1 year post-graft but they all had normal NK functions from the first month post-graft, these functions exceeding normal values on the second and third months post-graft. Finally, in 20 cases, dual-immunofluorescence staining permitted the demonstration that the autograft contained malignant cells before purging that were eliminated by the immunomagnetic depletion.

In order to test the numerous variable biological parameters which may contribute to the efficiency of the immunomagnetic depletion method, experiments have been carried out with different Burkitt lymphoma cell lines. The Hoechst dye method, a sensitive assay able to detect 3 log elimination, and a liquid culture assay suitable for identifying an elimination greater than 4 logs, were used to measure malignant cell elimination. These assays showed that the separation of bone marrow mononuclear cells on Ficoll-hypaque, the use of beads in excess, and a double treatment of the samples are needed to obtain optimal depletion of malignant cells. Under these conditions, the immunomagnetic procedure is capable of depleting 1% tumour cell infiltration at the lower limit of detection of a very sensitive culture assay (i.e. greater than 4 log elimination).

A new monoclonal antibody (S-L 11.14) raised against small cell lung cancer reacted with all but one neuroblastoma tumor cell sample tested and was relatively specific for such cells within the bone marrow. The ability of S-L 11.14 to eliminate neuroblastoma cells from the bone marrow with an immunomagnetic purging method was evaluated in an experimental model using the LAN.1 and SKNBE neuroblastoma cell lines as targets. Residual malignant cells after the purging procedure were quantified by the Hoechst staining method. The use of S-L 11.14 as a single reagent resulted in a 3-log elimination of malignant cells, a depletion equal to that obtained with a cocktail of five monoclonal antibodies currently used in clinical trials. The addition of the S-L 11.14 antibody to this cocktail did not enhance depletion.

Immunological analysis is complementary to morphological investigation to detect bone marrow (BM) metastases in neuroblastoma patients. It is essential at time of BM harvest for an autograft, since it is the only examination which allows a precise evaluation of the graft contamination by malignant cells. Simple indirect immunofluorescence staining with anti-neuroblastoma monoclonal antibodies (UJ13A and HSAN 1-2) allows a final detection of about 1% malignant cells in the BM, and 1% when cells are gathered in clumps. The use of an immunocytochemical method (alkaline phosphatase) together with double immunofluorescence staining permits to detect as few as one residual neuroblastoma cell in 10(4) normal ones. These two methods used together have allowed to assess the neuroblastoma nature of rare isolated cells with pseudo-lymphocytic aspect.