Characterization of anti-Thymoglobulin, anti-Atgam and anti-OKT3 IgG antibodies in human serum with an 11-min ELISA

The lack of supply and access to human tissue has prompted the development of xenotransplantation as a potential clinical modality for neural cell transplantation. The goal of the present study was to achieve a better understanding of the immune factors involved in neural xenograft rejection in primates. Initially, we quantified complement mediated cell lysis of porcine fetal neurons by primate serum and demonstrated that anti-C5 antibody treatment inhibited cell death. We then developed an immunosuppression protocol that included in vivo anti-C5 monoclonal antibody treatment, triple drug therapy (cyclosporine, methylprednisolone, azathioprine) and donor tissue derived from CD59 or H-transferase transgenic pigs and applied it to pig-to-primate neural cell transplant models. Pre-formed alphaGal, induced alphaGal and primate anti-mouse antibody (PAMA) titers were monitored to assess the immune response. Four primates were transplanted. The three CD59 neural cell recipients showed an induced anti-alphaGal response, whereas the H-transferase neural cell recipient exhibited consistently low anti-alphaGal titers. Two of these recipients contained surviving grafts as detected by immunohistochemistry using selected neural markers. Graft survival correlated with high dose cyclosporine treatment, complete complement blockade and the absence of an induced PAMA response to the murine anti-C5 monoclonal antibodies.

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“…The latter problem can be overcome in clinical studies by using fully humanized anti‐C5 antibodies (see Fig. 1) [37].…”

Section: Discussionmentioning

confidence: 99%

Immune parameters relevant to neural xenograft survival in the primate brain

Cicchetti

Fodor

Deacon

et al. 2003

Xenotransplantation

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“…Although monoclonal OKT-3 solved some of these issues with polyclonal preparations, it was still subject to a significant antimouse response, as OKT3 is an entirely mouse-derived antibody (Webster et al 2006). These xenogeneic antibodies can dramatically reduce the efficacy of these agents and extended/repeated use may lead to anaphylaxis and serum sickness (Prin Mathieu et al 1997;Regan et al 1997Regan et al , 2001). The first dose of these antibodies can be followed by fevers, chills, and gastointestinal, respiratory, and cardiac complications, mostly due to the release of pyrogenic cytokines such as IL-6 and TNF-a from target cell lysis (Debets et al 1989;Chatenoud et al 1990;Vallhonrat et al 1999).…”

Section: Challenges In Lymphodepletionmentioning

confidence: 99%

Lymphodepletional Strategies in Transplantation

Page

Kwun

et al. 2013

Cold Spring Harbor Perspectives in Medicine

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Because lymphocytes were shown to mediate transplant rejection, their depletion has been studied as a mechanism of preventing rejection and perhaps inducing immunologic tolerance. Agents that profoundly deplete lymphocytes have included monoclonal antibodies, cytotoxic drugs, and radiation. We have studied several such agents but focused on antibodies that deplete not only peripheral blood lymphocytes, but also lymph node lymphocytes. Depletion of lymph node T lymphocytes appears to permit peripheral tolerance at least for T cells in animal models. Nevertheless, B-cell responses may be resistant to such approaches, and T memory cells are likewise relatively resistant to depleting antibodies. We review the experimental and clinical approaches to depletion strategies and outline some of the pitfalls of depletion, such as limitations of currently available agents, duration of tolerance, infection, and malignancy. It is notable that most tolerogenic strategies that have been attempted experimentally and clinically include depleting agents even when they are not named as the underlying strategy. Thus, there is an implicitly acknowledged role for reducing the precursor frequency of donor antigen-specific lymphocytes when approaching the daunting goal of transplant tolerance.

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“…Use of polyclonal antibodies with xenogeneic V regions further reduces the induction of anti-idiotypic antibodies because, in a polyclonal antibody preparation, no one V region pair should be present in sufficient concentration to be immunogenic; and even if a particular V region pair induces an antiidiotypic response which eliminates it, it should be inconsequential because the activity of a polyclonal antibody preparation does not depend on a single member. This was shown by the antiidiotypic response of patients to the OKT3 antihuman thymocyte monoclonal antibody but the lack of an anti-idiotypic response to polyclonal rabbit or horse anti-human thymocyte globulins [Regan et al, 1997]. Similarly, human MAbs elicit an anti-idiotypic antibody response in humans [Koda et al, 2001], just as mouse MAbs elicit an anti-idiotypic response in mice [Paul, 2003].…”

Section: Future Perspectivesmentioning

confidence: 99%

Recombinant polyclonal antibodies for cancer therapy

Sharon¹,

Liebman²,

Williams³

2005

J of Cellular Biochemistry

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Although monoclonal antibodies are increasingly used for cancer therapy, remissions are only temporary due to emergence of tumor cell escape variants that are no longer affected by the antibody. The emergence of escape variants could be minimized by multi-targeting of tumor cells with polyclonal antibodies, which would also be more efficient than monoclonal antibodies at mediating effector functions for target destruction. A technology for generating recombinant polyclonal antibodies for cancer therapy has been developed based on the construction and selection of tumor-reactive Fab phage display libraries. The selected Fabs are mass-converted to full-length polyclonal antibody libraries (PCALs) of any isotype and any species. Prototypic PCALs generated against human colorectal cancer cell lines showed that libraries of diverse recombinant antibodies, enriched for reactivity to the cancer cells compared to normal human cells, can be obtained. The success of recombinant polyclonal antibodies as cancer therapeutics will depend on the ability to generate, characterize, and mass-produce PCALs with high ratios of cancer-to-normal reactivities that crossreact with many cancers of the same type.

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Characterization of anti-Thymoglobulin, anti-Atgam and anti-OKT3 IgG antibodies in human serum with an 11-min ELISA

Cited by 14 publications

References 5 publications

Immune parameters relevant to neural xenograft survival in the primate brain

Immune parameters relevant to neural xenograft survival in the primate brain

Lymphodepletional Strategies in Transplantation

Recombinant polyclonal antibodies for cancer therapy

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