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Although the DC-based immunotherapy of cancer has been promising in animal models, several questions need to be addressed in depth in humans: the generation of various types of dendritic cells, the analysis of their potential and the immunomonitoring of cancer patients. In our laboratory, our efforts have been focused on (i) the study of the cytotoxic activity of dendritic cells; (ii) the generation of a novel population of human dendritic cells from monocytes cultured in IL-3 and IFN-beta; (iii) the optimisation of the immunostimulatory properties of DC using Fas-ligand surexpression or adjuvants promoting DC/gamma-delta T cell interaction.

In cancer immunotherapy, the use of dendritic cells (DC) loaded with tumor-associated antigens (TAA) emerged as a promising strategy. We initiated 3 pilot clinical trials with immunological endpoints using TAA loaded autologous DC. These trials showed that this approach was safe and associated with the induction of potent TAA specific IFN-gamma responses, which were transient despite the providing a further help through KLH presentation. Subcutaneous (s.c.) IL-2 administration was associated with long-lasting TAA specific IL-5 production. Clinical responses were observed in about 1/3 of the patients. Further improvements will take advantage of the use of a new type of DC cells (IL-3/IFN-beta DC) and of tumor cell-DC hybrids.

Hypereosinophilia may be seen in the blood or tissues of cancer patients. A part of lymphomas, the tumors more frequently involved in such eosinophilia, are digestive and respiratory tract carcinomas. The prevalence of cancer-associated eosinophilia is very variable among the different kind of tumors. These cancer-associated eosinophilia are the results of the secretion by tumor or inflammatory cells of interleukin-3 and -5 and GM-CSF. The anti-cancer properties of eosinophilic polymorphonuclear are poorly understood and the prognostic significance of cancer-associated blood or tissue eosinophilia has not been assessed by controlled studies.

Investigation of the physiologic mechanisms involved in the activation of eosinophils is crucial to comprehend their role in the pathogenesis of allergic reactions. To overcome the difficulty of obtaining large numbers of eosinophils, we differentiated in vitro eosinophils from human umbilical cord blood mononuclear cells. These cells responded to fMLP or PAF with an increase in [Ca2+]i, associated with O2 production. Deprivation or chelation of extracellular calcium induced a reduction of fMLP or PAF-induced [Ca2+]i rise and O2- production. Similar results were obtained with extracellular Ni2+ addition. Chelation of intracellular calcium induced an inhibition of fMLP- or PAF-induced [Ca2+]i rise and a decrease in O2- production. Our results indicate that fMLP- and PAF-dependent O2- production in eosinophils requires intra- and extracellular Ca2+ and that Ca2+ influx is necessary for optimal activation.

Increasing progress has been made in the understanding of the biology of mast cells. The precursors of mast cells leave the bone marrow in a non-differentiated form as CD34+ cells. The presence of mast cells growth and differentiation factors controls in tissues maturation of different mast cells phenotypes. The main factors are the mast cell growth factor SCF (stem cell factor), NGF (Nerve Growth Factor), and IL-3 (Interleukin-3). The potential role of each of these factors in the airways is discussed. An altered production of these growth factors in the airways of asthmatic patients might be the cause of the presence of an increased number of mast cells and of phenotypic modifications in the bronchi of these patients.

Haematopoietic colony-stimulating factors are a group of molecules that can stimulate haemopoiesis. With the advent of recombinant DNA technology and the cloning of their genes, they can be utilized against malignant blood diseases. They might be useful in therapy of acute myelogenous leukaemia either by increasing the efficacy of antileukaemic drugs or by shortening the duration of granulocytopoenia following chemotherapy or bone marrow transplantation. Encouraging results have been obtained, but stimulation of leukaemic cells is not ruled out. Further clinical and biological investigations are required to provide insight into the role of cytokines in treatment of acute myelogenous leukaemia.

Accepting that there is "T-dependence" in the synthesis of IgE, it is certain that the cytokines, mediators that originate from activated lymphocytes, have an important role to play in allergic inflammation. The factor described by DE WECK, that assists activity of basophiles (BaPA) is identical in man with IL3, also known as Multi-CSF. Synthesis of IgE in vitro (and in vivo in mice) is dependent on IL4 and so T lymphocytes. IL5 and IL6 have a synergistic effect with the latter, though ILN gamma has an inhibitory effect. The two sub-populations TH1 and TH2 specialise, at least in mice, in the synthesis of specific cytokines the actions of which are unknown. The role of IL5 factor in the differentiation of eosinophils is shown.

International audience; Alloreactive T-cell clones obtained from cells infiltrating a human rejected kidney graft were shown to produce upon specific antigenic stimulation with interleukin 2, a factor triggering the proliferation of an interleukin 3 dependent murine cell line. The lymphokine responsible for this activity was a monomeric glycoprotein (MW = 41,000) exhibiting on one hand chemotactic as well as activating properties on murine and human eosinophils respectively, and on the other hand a burst promoting activity. Its biochemical and biological features strongly suggest that this factor cannot be likened to any known human lymphokine.

Since homogeneously purified Interleukin 3 can induce an increase in histamine synthesis by normal bone marrow cells (HCSF activity), it has been suggested that HCSF and IL3 could be identical. In this paper, we show evidence that HCSF activity can be obtained without any IL3 activity (determined by the proliferation of an IL3-dependent cell line). This distinction has been achieved in two different ways: (a) the physico-chemical separation of HCSF and IL3 from crude secondary MLC supernatants and (b) the spontaneous production by the P388D1 cell line of a factor possessing all the characteristics of HCSF without any IL3 activity. In addition, preliminary results show that anti-IL3 antibodies do not inhibit the increase in histamine synthesis induced by HCSF while it strongly diminishes that induced by IL3.

Interleukin-3 induces an increase in histamine synthesis, in the murine hematopoietic system. Evidence is given here that this biological activity also exists in the human hematopoietic system (fetal liver, bone marrow and cord blood), and is already detectable after 3 days of culture in the presence of interleukin-3.

Conditioned medium from P388 D1 cell line containing interleukin 1 (IL-1) and granulocyte macrophage colony stimulating factor (GM-CSF) can stimulate prostaglandin E2 (PGE2) production by murine bone marrow cells. In this work, we show that although GM-CSF (either purified from P388 D1 CM or murine recombinant GM-CSF) does not significantly alter bone marrow cell PGE2 production, its presence in P388 D1 CM is however necessary to induce this effect since the presence of anti GM-CSF antiserum completely abrogated the increase in PGE2 production in response to P388 D1 CM. In addition IL-1 tested alone does not not modify PGE2 release by bone marrow cells. However, the simultaneous addition of IL-1 and GM-CSF markedly increases PGE2 production. Thus, the ability of P388 D1 CM to stimulate PGE2 synthesis by bone marrow cells appears to result from a synergistic action between GM-CSF and IL-1.

Immune response implies reactions between immunocompetent cells. These reactions are made by direct contact between cells and via soluble factors. Among the latter, the interleukins, protein molecules produced during antigenic and mitogenic stimulation by the immunocompetent cells, intervene as modulators of the immune response. Interleukin-1, a protein synthesized by the activated macrophages, participates in the induction of interleukin-2 production by stimulated T-lymphocytes. Interleukin-2, a glycoprotein molecule, is the growth factor of activated T-lymphocytes by enabling their proliferation and clonal propagation. Interleukin-3, or Multi-colony stimulating factor, controls the production and the differentiation of haemopoietic cells and thus probably plays an important role in resistance to infections.