Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P14784 (IL-2 receptor)
 3,849 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Twenty-three monoclonal antibodies (MAbs) against the IL-2 receptor alpha-chain (CD25) were evaluated as ricin A-chain immunotoxins for the treatment of Hodgkin's disease. Primary screening used an indirect assay in which the cells were treated with the test antibody followed by a Fab' immunotoxin against mouse immunoglobulin. This screening identified 5 MAbs which inhibited protein synthesis in L540 Hodgkin cells by 50% at a concentration (IC50) of 6 x 10(-11) M or less: RFT5 gamma 1, RFT5 gamma 2a, B-B10, B-F2 and B-G3. These MAbs were then linked directly to deglycosylated ricin A-chain (dgA) and were confirmed to have potent and specific toxicity for L540 cells. The immunotoxins had the following potency order: RFT5 gamma 1 greater than RFT5 gamma 2a greater than B-B10 greater than B-F2 greater than B-G3. The most effective immunotoxin, RFT5 gamma 1.dgA, had an IC50 value of 7 x 10(-12) M, which is the same as that of whole ricin. In vivo, a single intravenous injection of 48 micrograms of RFT5 gamma 1.dgA, RFT5 gamma 2a.dgA, B-B10.dgA or B-F2 induced lasting complete remissions in 78, 66, 50 and 44%, respectively, of nude mice bearing subcutaneous solid L540 tumours of 0.7 cm diameter. Two tumours which regrew after B-B10.dgA treatment were re-established in tissue culture. Both had reduced sensitivity to B-B10.dgA in vitro but not to immunotoxins recognizing different antigens on Hodgkin cells. The MAbs that produced the most potent immunotoxins, RFT5 gamma 1, RFT5 gamma 2a and B-B10, had no significant cross-reactivity with normal human tissues outside the lymphoid system as judged from indirect immunoperoxidase staining of frozen sections. By contrast, B-F2 strongly stained normal human renal tubules.
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PMID:Immunotoxins constructed with anti-CD25 monoclonal antibodies and deglycosylated ricin A-chain have potent anti-tumour effects against human Hodgkin cells in vitro and solid Hodgkin tumours in mice. 191 43

Adult T cell leukemia (ATL) is an almost uniformly fatal malignancy of mature T cells associated with human T cell leukemia/lymphoma virus type 1 (HTLV-1) infection. Cells from this leukemia are characterized by the expression of large numbers of receptors for interleukin 2 (IL-2). In an attempt to prepare an immunotoxin with selective cytotoxicity for ATL cells, we conjugated anti-Tac, a monoclonal anti-IL-2 receptor antibody, to purified ricin A chains. Although unmodified anti-Tac had no effect on the protein synthesis of these cells, anti-Tac-ricin A chain conjugates produced half-maximal inhibition of protein synthesis in HTLV-1-infected leukemic T cell lines at concentrations of 2 to 6 X 10(-10) mol/L (ID50). An essentially identical ID50 was obtained with leukemic peripheral blood T lymphocytes isolated from two patients with ATL. In contrast, half-maximal inhibition of protein synthesis in HTLV-uninfected, IL-2 receptor-negative T and B cell lines required 200- to 1,000-fold higher concentrations of anti-Tac-ricin A chain conjugates. Both unconjugated anti-Tac and immunoaffinity-purified IL-2 completely inhibited the toxic effects of anti-Tac-ricin A, confirming the specificity of the conjugate-IL-2 receptor interaction. Clonogenic assays demonstrated that anti-Tac-ricin A chain was able to eliminate greater than 99.9% of an HTLV-1-infected T cell population at concentrations only marginally affecting IL-2 receptor-negative cells. The data presented demonstrate that anti-Tac-ricin A is selectively cytotoxic for HTLV-1-infected leukemic T cells in vitro and raises the future possibility of specific therapeutic intervention with immunotoxins in this disease.
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PMID:Adult T cell leukemia: a potential target for ricin A chain immunotoxins. 298 44

A T cell growth factor-dependent alloreactive human T cell line has been used to generate a monoclonal antibody B1.49.9 that reacts with an antigen present on most if not all mitogen or alloantigen activated T cells but not on resting T cells. The T lymphoblastoid cell line HUT-102 is also strongly reactive with B1.49.9 but all other T and non-T leukemia-lymphoma cell lines tested were negative. The B1.49.9 antigen is a glycoprotein of 55,000 Mr on mitogen or alloantigen activated T cells and 50,000 Mr on the cell line HUT-102. Pulse labeling experiments showed that a 40,000 Mr precursor (at approximately 0.7 h) which does not bind to ricin lectin precedes the appearance of the ricin-binding 55,000 Mr form. Comparisons of the monoclonal antibody anti-Tac, which recognizes the IL-2 receptor, to B1.49.9 suggest that B1.49.9 also recognizes a structure similar or identical to the IL-2 receptor.
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PMID:A 55,000 Mr surface antigen on activated human T lymphocytes defined by a monoclonal antibody. 641 69

Conjugates of IL-2 with the ribosome-inactivating protein gelonin were prepared using heterobifunctional reagents to link the proteins via disulfide, acid-labile, and noncleavable linkers. In each case, one protein was modified using 2-iminothiolane. The sulfhydryl groups so introduced were then reacted either with 2-nitro-5-dithiobenzoate groups or with iodoacetamido groups which had been introduced into the second protein. In the case of the acid-labile linkage, a reagent which forms a labile bond upon reaction with amino groups, 4-(iodoacetamido)-1-cyclohexene-1,2-dicarboxylic acid anhydride (its synthesis is described in this paper) was used to modify the toxin. The conjugates were separated from nonconjugated proteins by gel filtration on Sephadex G100 (SF). Each was analyzed with respect to its ribosome-inactivating activity, its ability to bind to the IL-2 receptor, and its in vitro cytotoxicity. The ribosome-inactivating activity of gelonin was unaffected by modification with 2-iminothiolane and was retained in conjugates prepared using this reagent. Modification of the toxin with 4-(iodoacetamido)-1-cyclohexene-1,2-dicarboxylic acid anhydride to form the acid-labile link drastically reduced the activity of the toxin. However, the activity of the toxin was recovered following acid treatment to release the native protein. Conjugates containing each type of linkage exhibited both specific binding and selective cytotoxicity toward cells expressing the IL-2 receptor. The most potent of these toxins, that containing the disulfide linkage, exhibited a cytotoxicity which was 2 orders of magnitude greater than that of unconjugated gelonin.
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PMID:Preparation and characterization of interleukin-2-gelonin conjugates made using different cross-linking reagents. 819 39

Conjugates of anti-CD25 monoclonal antibodies against cell surface IL-2 receptor with MLIA and RTA were prepared and investigated. Both of the immunotoxins had high specific cytotoxic activity on target cells. The IC50 value of the anti-CD25/MLIA immunotoxin was 15-fold greater than that of the anti-CD25/RTA. Previous studies of the anti-CD5 immunotoxins with MLIA and RTA showed that the anti-CD5/MLIA IT was 80-fold more active than anti-CD5/RTA IT [Tonevitsky et al. (1991) Int. J. Immunopharmacol. 13, 1037-1041]. The surface hydrophobicity of the MLI A-chain was 4-fold higher than that of the ricin A-chain as estimated by binding with ANS. In model experiments with small unilamellar DMPC liposomes, MLIA but not RTA increased the turbidity of liposome suspensions at pH 4.5. Our results indicate that the greater cytotoxic activity of the MLI A-chain immunotoxin probably provided a higher surface hydrophobicity of the protein and the ability to interact with phospholipid membranes.
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PMID:Immunotoxins containing A-chain of mistletoe lectin I are more active than immunotoxins with ricin A-chain. 877 96

Fusion toxins are hybrid proteins consisting of peptide ligands linked through amide bonds to polypeptide toxins. The ligand directs the molecule to the surface of target cells and the toxin enters the cytosol and induces cell death. Ricin is an excellent candidate for use in fusion toxins because of its extreme potency, the extensive knowledge of its atomic structure and the lack of prior immunological exposure in patients. We synthesized a baculovirus transfer vector with the polyhedrin promoter followed sequentially from the 5' end with DNA encoding the gp67A leader sequence, the tripeptide ADP, IL-2 (interleukin-2), another ADP tripeptide and RTB (ricin toxin B chain) with lectin-site mutations W37S and Y248H. Recombinant baculovirus was generated in Sf9 insect cells and used to infect Sf9 cells. Recombinant IL-2-RTB[W37S/Y248H] protein (fusion protein of IL-2 with modifications W37S and Y248H) was recovered at high yields from day 6 insect cell supernatants, partially purified by affinity chromatography and reassociated with RTA (ricin toxin A chain). The fusion toxin was soluble, immunoreactive with antibodies to RTB, IL-2 and RTA and had a molecular weight of 80 kDa by SDS-PAGE. The molecule reacted poorly with asialofetuin, but bound strongly to IL-2 receptor based on selective cytotoxicity to IL-2 receptor bearing cells. The specific cytotoxicity could be blocked with IL-2 but not lactose. Thus, we report a novel targeted fusion toxin protein with full biological activity.
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PMID:Characterization of a ricin fusion toxin targeted to the interleukin-2 receptor. 893 Nov 31

The data of a closed phase I/II trial in patients with resistant Hodgkin's lymphoma indicate promising results using a chemically linked anti-CD25 ricin-A immunotoxin (IT) (RFT5-SMPT-dgA). This IT is based on the high-affinity moab RFT5. Since recombinant DNA technology permits the readier production of large amounts of ITs, we constructed a new RFT5-based fusion toxin [RFT5(scFv)-ETA']. We isolated mRNA from the hybridoma cell line RFT5, synthesized first strand cDNA and performed RT-PCR. Amplified coding regions of the light and heavy chain variable domains were joined together with a synthetic (Gly4-Ser)3 linker. The resulting single chain variable fragment (scFv) was fused to a modified Pseudomonas aeruginosa exotoxin A (ETA') lacking its cell-binding domain I. After IPTG-induced expression in Escherichia coli, the 70 kDa His-tagged fusion protein [RFT5(scFv)-ETA'] was isolated by osmotic shock and sonication under denaturing conditions. The recombinant toxin was purified on a Ni2+-NTA chelating sepharose and eluted with 250 mM imidazole. Pooled protein was renatured, dialyzed and concentrated by precipitation. Binding properties of RFT5(scFv)-ETA' were assessed on the CD25-expressing cell line L540cy by ELISA, immunohistochemistry and FACS analysis. CD25-specific binding was confirmed by immunoprecipitation experiments with recombinant human IL-2 receptor alpha. The in vitro toxicity of the chimeric protein was tested on the Hodgkin-derived cell lines L540cy, L428, L1236, a monocyte cell line U937 and a Burkitt lymphoma cell line BL38. RFT5(scFv)-ETA' inhibited protein biosynthesis of L540cy and L428 cells by 50% at concentrations (IC50) of 18 and 12 ng/ml, respectively. CD25-specific toxicity was confirmed by competitive toxicity assays. These data confirm for the first time binding specificity and toxicity of a recombinant anti-CD25 immunotoxin, against Hodgkin-derived cell lines; its applicability on Hodgkin's lymphoma needs yet to be evaluated in vivo.
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PMID:Construction and in vitro evaluation of RFT5(scFv)-ETA', a new recombinant single-chain immunotoxin with specific cytotoxicity toward CD25+ Hodgkin-derived cell lines. 985 27