Bordetella pertussis attachment to respiratory epithelial cells can be impaired by fimbriae-specific antibodies

Bordetella pertussis attachment to host cells is a crucial step in colonization. In this study, we investigated the specificity of antibodies, induced either by vaccination or infection, capable of reducing bacterial adherence to respiratory epithelial cells. Both sera and purified anti-B. pertussis IgG or IgA fractions efficiently reduced attachment. This effect was found to be mediated mainly by fimbriae-specific antibodies. Antibodies with other specificities did not significantly interfere in the interaction of B. pertussis with respiratory epithelial cells, with the exception of antifilamentous hemaglutinin antibodies, which reduced bacterial attachment. However, this effect was smaller in magnitude than that observed in the presence of fimbriae-specific antibodies. The strong agglutinating activity of antifimbriae antibodies seems to be involved in this phenomenon.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Bordetella pertussis attachment to respiratory epithelial cells can be impaired by fimbriae-specific antibodies

Bordetella pertussis attachment to host cells is a crucial step in colonization. In this study, we investigated the specificity of antibodies, induced either by vaccination or infection, capable of reducing bacterial adherence to respiratory epithelial cells. Both sera and purified anti-B. pertussis IgG or IgA fractions efficiently reduced attachment. This effect was found to be mediated mainly by fimbriae-specific antibodies. Antibodies with other specificities did not significantly interfere in the interaction of B. pertussis with respiratory epithelial cells, with the exception of antifilamentous hemaglutinin antibodies, which reduced bacterial attachment. However, this effect was smaller in magnitude than that observed in the presence of fimbriae-specific antibodies. The strong agglutinating activity of antifimbriae antibodies seems to be involved in this phenomenon.Centro de Investigación y Desarrollo en Fermentaciones Industriale

Renaissance of cancer therapeutic antibodies

In the past five years therapeutic monoclonal antibodies have established themselves as perhaps the most important and rapidly expanding class of therapeutic drugs. More than 25% of pharmacological agents that are currently under development are based on antibodies and the total income generated from them in 2002 exceeded $3 billion, and is predicted to rise to$10–20 billion by 2010. Many experts feel that antibodies directed at cancer targets are likely to dominate the market for the foreseeable future. In this review, we will discuss some of the factors that, after more than 25 years of development, have led to this transformation in the antibody field. Current technology makes the generation of fully-human antibodies a routine procedure. However, selection of appropriate disease targets still represents a challenge. Here we discuss factors that make an effective antibody target and provide an overview of the major issues that are likely to shape this exciting field over the next decade

Therapeutic efficacy of FcgammaRI/CD64-directed bispecific antibodies in B-cell lymphoma

CD64 (Fc?RI) receptors represent highly potent trigger molecules for activated polymorphonuclear cells (PMN) and mediate lysis of a range of tumors in the presence of appropriate monoclonal antibodies. An huCD64 transgenic mouse model designed to analyze the therapeutic activity of a panel of bispecific F(ab')2(BsAb) in retargeting granulocyte–colony-stimulating factor (G-CSF)–activated PMN against syngeneic B-cell lymphomas is reported. This model allows careful analysis of the individual elements of the therapeutic process. BsAb were directed against immunoglobulin-idiotype (Id), major histocompatibility class II (MHC II), or CD19 on the tumors and huCD64 on the effectors. In vitro cytotoxicity assays and in vivo tumor tracking showed that, provided effectors were activated with G-CSF, all 3 derivatives destroyed and cleared lymphoma cells, with (huCD64?×?MHC II) proving by far the most cytotoxic in vitro. However, though all derivatives delivered some survival advantage, only the [huCD64?×?Id] BsAb provided long-term protection to tumor-bearing animals. These results demonstrate that CD64-recruited cytotoxic effectors operate in vivo but that the (huCD64?×?Id) conferred an additional anti-tumor function essential for long-term protection. T-cell depletion studies demonstrated that this extra therapeutic activity with [huCD64?×?Id] was totally dependent on CD4 and CD8 T cells and that mice, once “cured” with BsAb, were resistant to tumor rechallenge. These findings indicate that CD64 is an effective trigger molecule for delivering cytokine-activated PMN against tumor in vivo and that, provided tumor targets are selected appropriately, CD64-based BsAb can establish long-term T-cell immunity. <br/

Mechanisms of G-CSF- or GM-CSF-stimulated tumor cell killing by Fc receptor-directed bispecific antibodies

Studies with gene-modified mice have recently reinforced the importance of Fc receptor-mediated effector mechanisms for the therapeutic efficacy of rituxan and herceptin — two clinically approved antibodies for the treatment of tumor patients. We investigated Fc receptor-dependent tumor cell killing by mononuclear and granulocytic effector cells — comparing human IgG1 antibodies against CD20 or HER-2/neu with their respective Fc?RI (CD64)-, Fc?RIII (CD16)-, or Fc?RI (CD89)-directed bispecific derivatives. With blood from healthy donors as effector source, human IgG1 and Fc?RIII (CD16)-directed bispecific antibodies proved most effective in recruiting mononuclear effector cells, whereas tumor cell killing by granulocytes was most potently triggered by Fc?RI-directed bispecific constructs. Granulocyte-mediated tumor cell lysis was significantly enhanced when blood from G-CSF- or GM-CSF-treated patients was investigated. Interestingly, however, both myeloid growth factors improved effector cell recruitment by different mechanisms, which were furthermore dependent on the tumor target antigen, and on the selected cytotoxic Fc receptor

Mechanisms of G-CSF- or GM-CSF-stimulated tumor cell killing by Fc receptor-directed bispecific antibodies

Studies with gene-modified mice have recently reinforced the importance of Fc receptor-mediated effector mechanisms for the therapeutic efficacy of rituxan and herceptin — two clinically approved antibodies for the treatment of tumor patients. We investigated Fc receptor-dependent tumor cell killing by mononuclear and granulocytic effector cells — comparing human IgG1 antibodies against CD20 or HER-2/neu with their respective Fc?RI (CD64)-, Fc?RIII (CD16)-, or Fc?RI (CD89)-directed bispecific derivatives. With blood from healthy donors as effector source, human IgG1 and Fc?RIII (CD16)-directed bispecific antibodies proved most effective in recruiting mononuclear effector cells, whereas tumor cell killing by granulocytes was most potently triggered by Fc?RI-directed bispecific constructs. Granulocyte-mediated tumor cell lysis was significantly enhanced when blood from G-CSF- or GM-CSF-treated patients was investigated. Interestingly, however, both myeloid growth factors improved effector cell recruitment by different mechanisms, which were furthermore dependent on the tumor target antigen, and on the selected cytotoxic Fc receptor