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  • American Society of Hematology  (4)
  • 1
    In: Blood, American Society of Hematology, Vol. 90, No. 11 ( 1997-12-01), p. 4485-4492
    Abstract: Promising results from clinical trials with unconjugated antibodies stimulated renewed interest in immune effector mechanisms of monoclonal antibodies (MoAbs). We investigated the potential of IgA as antibody isotype for cell- or complement-mediated tumor cell lysis and assessed the potential of its myeloid Fc receptor, FcαRI (CD89), as trigger molecule for bispecific antibody (BsAb)-mediated immunotherapy. Comparing hapten-directed antibodies of human IgA2 with IgG1 or IgG3 isotypes, we found all three to mediate effective killing of sensitized tumor target cells in whole blood assays. Analysis of effector mechanisms showed IgG-mediated lysis to be predominantly complement-dependent, whereas IgA-dependent killing was primarily effector cell-mediated. A comparison of effector cell populations in antibody-dependent cell-mediated cytotoxicity (ADCC) showed neutrophils to be most important for IgA-dependent tumor cell killing, involving FcαRI as shown with Fc receptor blocking antibodies. Reverse ADCC experiments against target cells sensitized with Fc receptor antibodies, or assays with FcαRI-directed bispecific antibodies confirmed FcαRI as effective trigger molecule in polymorphonuclear neutrophil (PMN)-mediated lysis. During granulocyte colony-stimulating factor (G-CSF ) therapy, (FcαRI × HER-2/neu) bispecific antibodies induced enhanced killing of HER-2/neu positive SK-BR–3 breast cancer cells in whole blood assays. This enhanced cytotoxicity was paralleled by increased PMN counts, which lead to higher effector to target cell ratios in G-CSF–primed blood. Furthermore, bispecific antibodies, directed to FcαRI and Candida albicans, enhanced neutrophils' phagocytosis of fungi. In summary, these results identify IgA as an effective antibody isotype for immunotherapy, working primarily via FcαRI on neutrophils. They suggest FcαRI-directed bispecific antibodies and G-CSF to be an attractive combination for malignant or infectious diseases.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1997
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 2
    In: Blood, American Society of Hematology, Vol. 91, No. 6 ( 1998-03-15), p. 1858-1863
    Abstract: Seroepidemiology and polymerase chain reaction studies have strongly suggested that human herpesvirus type 8 (HHV-8) is associated with Kaposi's sarcoma, Castleman's disease, and body cavity-based lymphoma. The genome of HHV-8 harbors a viral analogue of the interleukin-6 (IL-6) gene. The amino acid sequence of the viral IL-6 (vIL-6) protein is 24.7% identical to human IL-6 (hIL-6). IL-6 as a B-cell growth and differentiation factor is known to play an essential role in the pathophysiology of B-cell tumors. Thus, it seems possible that virus-encoded IL-6 contributes to malignant growth of HHV-8–positive B-cell lymphatic tumors. We have tested a preparation of HHV-8–derived IL-6 for the ability to promote the proliferation of the human myeloma cell line INA-6, which is strictly dependent on exogenous IL-6 for growth and survival. Viral IL-6 significantly induced DNA synthesis of INA-6 cells, but required much more protein on a weight basis when compared with hIL-6 for maximal proliferation. The proliferative effect of vIL-6 was almost completely inhibited by a combination of anti–IL-6 receptor (IL-6R) and anti-gp130 antibodies or IL-6R superantagonist Sant7 and anti-gp130 antibodies. This report demonstrates that vIL-6 has proliferative activity on human cells and that the IL-6R and gp130 are involved in vIL-6 signaling in the myeloma cell line INA-6.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1998
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 3
    In: Blood, American Society of Hematology, Vol. 91, No. 6 ( 1998-03-15), p. 1858-1863
    Abstract: Seroepidemiology and polymerase chain reaction studies have strongly suggested that human herpesvirus type 8 (HHV-8) is associated with Kaposi's sarcoma, Castleman's disease, and body cavity-based lymphoma. The genome of HHV-8 harbors a viral analogue of the interleukin-6 (IL-6) gene. The amino acid sequence of the viral IL-6 (vIL-6) protein is 24.7% identical to human IL-6 (hIL-6). IL-6 as a B-cell growth and differentiation factor is known to play an essential role in the pathophysiology of B-cell tumors. Thus, it seems possible that virus-encoded IL-6 contributes to malignant growth of HHV-8–positive B-cell lymphatic tumors. We have tested a preparation of HHV-8–derived IL-6 for the ability to promote the proliferation of the human myeloma cell line INA-6, which is strictly dependent on exogenous IL-6 for growth and survival. Viral IL-6 significantly induced DNA synthesis of INA-6 cells, but required much more protein on a weight basis when compared with hIL-6 for maximal proliferation. The proliferative effect of vIL-6 was almost completely inhibited by a combination of anti–IL-6 receptor (IL-6R) and anti-gp130 antibodies or IL-6R superantagonist Sant7 and anti-gp130 antibodies. This report demonstrates that vIL-6 has proliferative activity on human cells and that the IL-6R and gp130 are involved in vIL-6 signaling in the myeloma cell line INA-6.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1998
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
  • 4
    In: Blood, American Society of Hematology, Vol. 90, No. 11 ( 1997-12-01), p. 4485-4492
    Abstract: Promising results from clinical trials with unconjugated antibodies stimulated renewed interest in immune effector mechanisms of monoclonal antibodies (MoAbs). We investigated the potential of IgA as antibody isotype for cell- or complement-mediated tumor cell lysis and assessed the potential of its myeloid Fc receptor, FcαRI (CD89), as trigger molecule for bispecific antibody (BsAb)-mediated immunotherapy. Comparing hapten-directed antibodies of human IgA2 with IgG1 or IgG3 isotypes, we found all three to mediate effective killing of sensitized tumor target cells in whole blood assays. Analysis of effector mechanisms showed IgG-mediated lysis to be predominantly complement-dependent, whereas IgA-dependent killing was primarily effector cell-mediated. A comparison of effector cell populations in antibody-dependent cell-mediated cytotoxicity (ADCC) showed neutrophils to be most important for IgA-dependent tumor cell killing, involving FcαRI as shown with Fc receptor blocking antibodies. Reverse ADCC experiments against target cells sensitized with Fc receptor antibodies, or assays with FcαRI-directed bispecific antibodies confirmed FcαRI as effective trigger molecule in polymorphonuclear neutrophil (PMN)-mediated lysis. During granulocyte colony-stimulating factor (G-CSF ) therapy, (FcαRI × HER-2/neu) bispecific antibodies induced enhanced killing of HER-2/neu positive SK-BR–3 breast cancer cells in whole blood assays. This enhanced cytotoxicity was paralleled by increased PMN counts, which lead to higher effector to target cell ratios in G-CSF–primed blood. Furthermore, bispecific antibodies, directed to FcαRI and Candida albicans, enhanced neutrophils' phagocytosis of fungi. In summary, these results identify IgA as an effective antibody isotype for immunotherapy, working primarily via FcαRI on neutrophils. They suggest FcαRI-directed bispecific antibodies and G-CSF to be an attractive combination for malignant or infectious diseases.
    Type of Medium: Online Resource
    ISSN: 1528-0020 , 0006-4971
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 1997
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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