Production of human monoclonal and polyclonal antibodies in TransChromo animals.
ABSTRACT We have developed TransChromo (TC) technology, which enables the introduction of megabase-sized segments of DNA into cells. We have used this approach to derive mice that carry megabases of human DNA by the use of a human chromosome fragment (HCF) as a vector. TC technology has been applied to the construction of the TC Mouse,trade mark which incorporates entire human immunoglobulin (hIg) loci. TC Mouse expresses a fully diverse repertoire of hIgs, including all the subclasses of IgGs (IgG1-G4). Immunization of the TC Mouse with various human antigens produced antibody responses comprised of human antibodies. Furthermore, it was possible to obtain hybridoma clones expressing fully human antibodies specific for the target human antigen. However, because of the instability of the Igkappa locus-bearing HCF2, the efficiency of hybridoma production was less than one-tenth of that observed in normal mice. An instant solution to this problem was to cross-breed the Kirin TC Mouse carrying the HCF14, which was stable in mouse cells, with the Medarex YAC-transgenic mouse carrying about 50% of the hIgVkappa gene segments as a region that is stably integrated into the mouse genome. The resulting mouse, dubbed the KM Mouse, performed as well as normal mice with regard to immune responsiveness and efficiency of hybridoma production. Another application of TC technology is the production of polyclonal antibodies in large animals such as chickens and cows. To test the efficacy of human polyclonal antibodies derived from TC animals, feasibility studies were performed using antisera and purified gamma-globulin from TC mice immunized with Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), or Japanese encephalitis virus (JEV). The TC mouse-derived antisera and gamma-globulin showed a much higher titer and efficacy in terms of the neutralizing activity of the pathogens in vitro and in vivo than either human serum or gamma-globulin prepared from human blood.
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ABSTRACT: The contribution of the complement system to the control of tumour growth has been neglected for a long time as the major emphasis has been put mainly on cell-mediated immune response against cancer. With the introduction of monoclonal antibodies in cancer immunotherapy complement has come into play with a great potential as effector system. Complement has a number of advantages over other effector systems in that it is made of molecules that can easily penetrate the tumour tissue and a large majority, if not all, of the components of this system can be supplied locally by many cells at tissue site. Further advances are being made to increase the anti-tumour efficiency of the complements system using C-fixing antibodies that are modified in the Fc portion to be more active in complement activation. Another strategy currently investigated is essentially based on the use of a combination of two antibodies directed against different molecules or different epitopes of the same molecule expressed on the cell surface in order to increase the number of the binding sites for the antibodies on the tumor cells and the chance for them to activate complement more efficiently. One of the problems to solve in exploiting complement as an effector system in cancer immunotherapy is to neutralize the inhibitory effect of complement regulatory proteins which are often over-expressed on tumour cells and represent a mechanism of evasion of these cells from complement attack. This situation can be overcome using neutralizing antibodies to target onto tumour cells together with the specific antibodies directed against tumor specific antigens. This is an area of active investigation and the initial data that start to be available from animal models seem to be promising.Immunology Letters 08/2007; 111(1):6-13. · 2.53 Impact Factor
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ABSTRACT: Molecular targeting therapy has become a relevant therapeutic strategy for cancer. There are several monoclonal antibodies used for the treatment of malignant tumors. Radioimmunoconjugate is composed of antibody and radionuclide showing a synergistic effect of radiation and immunemediated cellular toxicity and thereby enabling increased efficacy and minimizing toxicity. Radioimmunotherapy using 131I- and 90Y-labeled anti-CD20 monoclonal antibodies is now indicated for the treatment of patients with CD20 antigen-expressing relapsed or refractory, low-grade or transformed non-Hodgkin's lymphoma (NHL), including patients who are refractory to anti-CD20 monoclonal antibody (rituximab) therapy in the United States. It has been exhibiting favorable anti-tumor efficacy in patients with NHL as compared with rituximab. Myelosuppression is the main side effect associated with the radioimmunotherapy but is usually reversible, and nonhematologic adverse reactions are mild to moderate. Following the impressive results of therapy using radiolabeled monoclonal antibodies for NHL, radioimmunotherapy for solid tumors has been examined; however, the results were unfavorable and did warrant further clinical trials as a single agent. Future studies on radioimmunotherapy for solid tumors should focus on the new strategies of targeting such as locoregional administration for intraperitoneal dissemination, and combination therapy with chemotherapy or cytostatic therapy. Although radioimmunotherapy for NHL has shown excellent results comparable to aggressive chemotherapy without severe adverse effects, additional clinical trials should be performed to define the proper role of radioimmunoconjugates as a relevant strategy for cure of NHL.Annals of Nuclear Medicine 08/2005; 19(5):355-65. · 1.50 Impact Factor