Search results for: Feline Leukemia virus antibody, Monoclonal Antibodies, Host Mouse
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Antileukemia and antitumor effects of the graft-versus-host disease: a new immunovirological approach.
In leukemic mice, the native host's explicit and well-defined immune reactions to the leukemia virus (a strong exogenous antigen) and to leukemia cells (pretending in their native hosts to be protected "self" elements) are extinguished and replaced in GvHD (graft-versus-host disease) by those of the immunocompetent donor cells. In many cases, the GvHD-inducer donors display genetically encoded resistance to the leukemia virus. In human patients only antileukemia and anti-tumor cell immune reactions are mobilized; thus, patients are deprived of immune reactions to a strong exogenous antigen (the elusive human leukemia-sarcoma retroviruses). The innate and adaptive immune systems of mice have to sustain the immunosuppressive effects of leukemia-inducing retroviruses. Human patients due to the lack of leukemiainducing retroviral pathogens (if they exist, they have not as yet been discovered), escape such immunological downgrading. After studying leukemogenic retroviruses in murine and feline (and other mammalian) hosts, it is very difficult to dismiss retroviral etiology for human leukemias and sarcomas. Since no characterized and thus recognized leukemogenic-sarcomagenic retroviral agents are being isolated from the vast majority of human leukemias-sarcomas, the treatment for these conditions in mice and in human patients vastly differ. It is immunological and biological modalities (alpha interferons; vaccines; adoptive lymphocyte therapy) that dominate the treatment of murine leukemias, whereas combination chemotherapy remains the main remission-inducing agent in human leukemias-lymphomas and sarcomas (as humanized monoclonal antibodies and immunotoxins move in). Yet, in this apparently different backgrounds in Mus and Homo, GvHD, as a treatment modality, appears to work well in both hosts, by replacing the hosts' anti-leukemia and anti-tumor immune faculties with those of the donor. The clinical application of GvHD in the treatment of human leukemias-lymphomas and malignant solid tumors remains a force worthy of pursuit, refinement and strengthening. Graft engineering and modifications of the inner immunological environment of the recipient host by the activation or administration of tumor memory T cells, selected Treg cells and natural killer (NKT) cell classes and cytokines, and the improved pharmacotherapy of GvHD without reducing its antitumor efficacy, will raise the value of GvHD to the higher ranks of the effective antitumor immunotherapeutical measures. Clinical interventions of HCT/HSCT (hematopoietic cell/stem cell transplants) are now applicable to an extended spectrum of malignant diseases in human patients, being available to elderly patients, who receive non-myeloablative conditioning, are re-enforced by post-transplant donor lymphocyte (NK cell and immune T cell) infusions and post-transplant vaccinations, and the donor cells may derive from engineered grafts, or from cord blood with reduced GvHD, but increased GvL/GvT-inducing capabilities (graft-versus leukemia/tumor). Post-transplant T cell transfusions are possible only if selected leukemia antigen-specific T cell clones are available. In verbatim quotation: "Ultimately, advances in separation of GvT from GvHD will further enhance the potential of allogeneic HCT as a curative treatment for hematological malignancies" (Rezvani, A.R. and Storb, R.F., Journal of Autoimmunity 30:172-179, 2008 (see in the text)). It may be added: for cure, a combination of the GvL/T effects with new targeted therapeutic modalities, as elaborated on in this article, will be necessary.Joseph G Sinkovics
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Induction of feline leukaemia virus-neutralizing antibodies by immunization with synthetic peptides derived from the FeLV env gene.
The surface glycoprotein, gp70, of feline leukaemia virus (FeLV) contains sites which are important in inducing neutralizing antibodies. Using synthetic peptides corresponding to nucleotide sequence 729-957 (amino acid sequence 243-319) of FeLV-A/Glasgow-1, the antigenicity and immunogenicity of this part of the viral surface glycoprotein were investigated. The region contains two highly conserved domains separated by a variable region (VR4), when compared with FeLV of subgroups B and C, and an epitope known to be involved in virus neutralization is located in the N-terminal conserved domain. Five murine monoclonal antibodies generated by immunization with virus were found to be directed to this domain and four were virus-neutralizing. Polyclonal mouse, rabbit and cat anti-FeLV antisera, which were virus-neutralizing, were directed to B-cell epitopes in the peptides. To determine if those synthetic peptides could induce neutralizing antibodies, rabbits were immunized with the peptides, singly or in combination. Antibody responses were measured by ELISA for anti-peptide, anti-FeLV and anti-gp70 activity, by immunoblotting, by membrane immunofluorescence and by virus-neutralization tests. Virus-neutralizing antibodies were induced by FeLV gp70 peptides and there was a synergistic effect on antibody production when a combination of peptides covering amino acid sequence 243-319 of FeLV-A was used. In a second experiment, six rabbits and six cats were immunized with a combination of two peptides, which covered the above-defined FeLV gp70 sequence. Comparisons were made of the responses to these peptides incorporated into immunostimulating complexes (ISCOMs) via myristic acid tails, inoculated with 'empty' ISCOMs, or with Al(OH)3. Complete Freund's adjuvant (CFA) had a very strong potentiating effect on the induction of antibodies and immunization with peptides incorporated into ISCOMs was superior to immunization using adjuvants other than CFA. It is very promising that not only in rabbits, but also in the natural host of FeLV, the cat, anti-FeLV gp70 (peptides) antibodies could be induced by FeLV gp70 peptides.K Weijer, A Pfauth, R van Herwijnen, O Jarrett, R H Meloen, C Tomee, A D Osterhaus