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  • 1
    ISSN: 1432-0851
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thein vivo administration of repetitive weekly cycles of interleukin-2 (IL-2) to patients with cancer enhances the ability of freshly obtained peripheral blood lymphocytes (PBL) to lyse both the natural-killer(NK)-susceptible K562 and the NK-resistant Daudi targets. Lysis of both targets is significantly augmented by inclusion of IL-2 in the medium during the cytotoxicity assay. This boost is much greater for cells obtained following thein vivo IL-2 therapy than for cells obtained prior to the initiation of therapy or for cells from healthy control donors. In addition to direct lytic activity, the PBL obtained followingin vivo IL-2 show a rapid increase in lymphokine-activated killer (LAK) activity with more prolongedin vitro IL-2 exposure, indicating that LAK effectors primedin vivo respond with “secondary-like” kinetics to subsequent IL-2in vitro. Lymphocytes from healthy control individuals, cultured in IL-2 under conditions attempting to simulate thein vivo IL-2 exposure, function similarly to PBL obtained from patients following IL-2, in that low-level LAK activity was significantly boosted by inclusion of IL-2 during the cytotoxic assay and the cells also responded with secondary-like kinetics to subsequent IL-2in vitro. The augmentation of the LAK effect was also dependent on the dose of IL-2 added during the 4-h51Cr-release cytotoxicity assay, with higher doses of IL-2 having a more pronounced effect. While continuous infusion of IL-2 induces a greater cytotoxic potential per milliliter of blood obtained from patients, the peak serum IL-2 levels attained are greater with bolus IL-2 infusions. These pharmacokinetic results, together with the IL-2 dose dependence of LAK activity generatedin vivo shown in this report, suggest that a combination of treatment with bolus IL-2 infusions superimposed on continuous IL-2 infusion may transiently expose IL-2 dependent LAK cells, activatedin vivo, to higher concentrations of IL-2, facilitating theirin vivo cytotoxic potential.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0851
    Keywords: Key words Interleukin-2 ; Antitumor antibody ; Targetted immunotherapy ; Ganglioside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The fusion protein formed from ch14.18 and interleukin-2 (ch14.18–IL-2), shown to exhibit antitumor efficacy in mouse models, consists of IL-2 genetically linked to each heavy chain of the ch14.18 chimeric anti-GD2 monoclonal antibody. The purpose of this study was to determine the pharmacokinetics of ch14.18–IL-2 in mice and assess its stability in murine serum. Following i.v. injection, the fusion protein was found to have a terminal half-life of 4.1 h. Detection of IL-2 following injection of the ch14.18–IL-2 fusion protein showed a similar half-life, indicating that the fusion protein prolongs the circulatory half-life of IL-2. Detection of human IgG1 following injection of ch14.18–IL-2 showed a terminal half-life of 26.9 h. These data suggested that the native fusion protein is being altered in vivo, resulting in a somewhat rapid loss of detectable IL-2, despite prolonged circulation of its immunoglobulin components. In vitro incubation of the ch14.18–IL-2 fusion protein in pooled mouse serum at 37 °C for 48 h resulted in a loss of its IL-2 component, as detected in enzyme-linked immunosorbent assay systems and in proliferation assays. Polyacrylamide gel electrophoresis and Western blot analysis of the fusion protein incubated in mouse serum at 37 °C indicated that the ch14.18–IL-2 is cleaved, resulting in a loss of the 67-kDa band (representing the IL-2 linked to the IgG1 heavy chain) and the detection of a band of more than 50 kDa, slightly heavier than the IgG1 heavy chain itself. This suggests that the fusion protein is being cleaved in vitro within the IL-2 portion of the molecule. These studies show that (1) ch14.18–IL-2 prolongs the circulatory half-life of IL-2 (compared to that of soluble IL-2) and (2) the in vivo clearance of the fusion protein occurs more rapidly than the clearance of the ch14.18 antibody itself, possibly reflecting in vivo cleavage within the IL-2 portion of the molecule, resulting in loss of IL-2 activity.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0851
    Keywords: Key words Human ; Blood ; Cellular activation ; Transcription factors ; Human-clinical studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Administration of the cytokine interleukin-2 (IL-2) can result in therapeutic benefits for individuals with renal cell carcinoma and melanoma. Here we report an analysis of the transcription factor families AP-1, Sp1, NF-κB, and signal transducers and activators of transcription (STAT) in cancer patients’ lymphocytes before and after IL-2 immunotherapy, as assessed by a gel-shift assay. An in vitro surrogate of IL-2 immunotherapy is the incubation of fresh peripheral blood mononuclear cells (PBMC) from healthy individuals in IL-2 for several days, resulting in the production of lymphokine-activated killer (LAK) activity in these cultures. One purpose of this study was to describe the profile of transcription factor activation in these different populations, and assess whether the patterns observed correlated with functional differences in these cells. Prior to in vivo IL-2 administration, the typical binding pattern of transcription factors in PBMC from patients resembled that seen in fresh PBMC from healthy individuals. Over a 3-week course of IL-2 therapy, in most patients the binding patterns of AP-1, Sp1, and NF-κB proteins changed to resemble those seen in PBMC activated by IL-2 in vitro. However, the cells obtained from IL-2-treated patients did not have low-level constitutive expression of STAT binding factors as did LAK cells. When these patient cells were further stimulated by IL-2 in vitro, additional differences in STAT induction patterns were noted. These data provide further information on the molecular events occurring in immune cells generated through in vivo and in vitro administration of IL-2, and further document that there is not a precise congruence between PBMC activated in vivo and in vitro by IL-2.
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