Anti-galactose-α(1,3) galactose antibody production in α1,3-galactosyltransferase gene knockout mice after xeno and allo transplantation

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Classic hyperacute rejection is dependent on the activation of the terminal components of complement. Recently, xenoantibodies with limited abilities to activate the classical pathway of complement in vitro have been implicated in the acute vascular rejection of xenografts. It is unclear how these Abs affect their pathogenic activities in vivo. In this study, we demonstrate the ability of an anti-Gal-α1,3Gal (Gal) IgG1, with modest complement-activating abilities in vitro, to induce xenograft rejection. This rejection was dependent on the activation of complement, on FcγR-mediated interactions, and on the presence of NK cells. Inhibition of any one of these factors resulted in the abrogation of IgG1-mediated rejection. In contrast, an anti-Gal IgG3 mAb induced classic, hyperacute rejection that was solely dependent on complement activation. Our observations implicate two types of IgG-mediated rejection; one that is dependent on complement activation, and a second that is uniquely dependent on complement, FcγR, and NK cells.

Section: Role Of Nk Cells In Anti-gal Igg1-and Igg3-mediated Rejectionsupporting

confidence: 64%

Cutting Edge: NK Cells Mediate IgG1-Dependent Hyperacute Rejection of Xenografts

Yin

Zeng

et al. 2004

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“…The Gal Ϫ/Ϫ mouse represents a model immunological system for studying anti-Gal responses to Gal ϩ/ϩ xenografts (23)(24)(25)(26). We have used this system to produce a series of anti-Gal hybridomas derived from naive Gal Ϫ/Ϫ mice and from Gal Ϫ/Ϫ mice after rat to mouse heterotopic cardiac xenotransplantation (27).…”

mentioning

confidence: 99%

The In Vitro and In Vivo Effects of Anti-Galactose Antibodies on Endothelial Cell Activation and Xenograft Rejection

Yin

Naziruddin

et al. 2003

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We have previously produced a series of antigalactose (anti-Gal) hybridomas and characterized their heavy chain gene usage. Here we have quantified the affinity of these Abs for the α-Gal epitope and characterized their in vitro effects on endothelial cell activation and apoptosis. We report that anti-Gal mAbs derived from Gal−/− mice show a range of affinity for the α-Gal epitope, and that affinity was generally increased as the VH gene usage transitioned from germline sequences to sequences exhibiting somatic maturation. Despite an 85-fold range in affinity, all the anti-Gal mAbs examined induced α-Gal-specific endothelial cell activation, and after prolonged exposure induced endothelial cell apoptosis in a complement-independent manner. Only murine anti-Gal mAbs of the IgM or IgG3 subclass, but not IgG1, were effective at initiating complement-dependent cell lysis. Using a novel rat to mouse xenograft model, we examined the in vivo ability of these mAbs to induce xenograft rejection and characterized the rejection using histology and immunohistochemistry. Infusion of complement-fixing IgG3 mAbs resulted in either hyperacute rejection or acute vascular rejection of the xenograft. Surprisingly, infusion of an equal amount of a high affinity anti-Gal IgG1 mAb, that fixed complement poorly also induced a rapid xenograft rejection, which we have labeled very acute rejection. These studies emphasize the importance of in vivo assays, in addition to in vitro assays, in understanding the role of anti-Gal IgG-mediated tissue injury and xenograft rejection.

“…Dengping Yin, 1 D espite the development of new approaches and the clarification of the mechanisms of tolerance induction in murine models, transplantation tolerance remains an elusive clinical goal. Both central and peripheral mechanisms have been implicated in the induction of tolerance in mice.…”

Section: Ifn-␥ Production Is Specifically Regulated By Il-10 In Mice mentioning

confidence: 99%

“…Central deletion of alloreactive cells has traditionally been thought to induce the most durable form of donor-specific tolerance. This type of tolerance requires the establishment of a chimeric state within the host, usually after the administration of donor bone marrow cells, which is responsible for deleting alloreactive cells in the thymus or bone marrow (1,2). In the presence of this chimeric state, the host can accept donor organs without the need for immunosuppressive drugs (3).…”

Section: Ifn-␥ Production Is Specifically Regulated By Il-10 In Mice mentioning

confidence: 99%

IFN-γ Production Is Specifically Regulated by IL-10 in Mice Made Tolerant with Anti-CD40 Ligand Antibody and Intact Active Bone

Yin¹,

Dujovny²,

Ma³

et al. 2003

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We have developed a strategy to induce tolerance to allografts, involving cotransplantation of allogeneic intact active bone and transient anti-CD40 ligand mAb therapy. Tolerance induced by this approach in C57BL/6 mice receiving BALB/c hearts is not mediated by deletional mechanisms, but by peripheral regulatory mechanisms. Tolerance is associated with diminished ex vivo IFN-γ production that is donor specific, and a reduction in the frequency of IFN-γ-producing cells. Splenocytes from mice tolerant to BALB/c grafts, but sensitized to third-party C3H skin grafts, demonstrated normally primed ex vivo IFN-γ responses to C3H stimulators. Neutralizing anti-IL-10 and anti-IL-10R, but not anti-TGF-β, anti-IL-4, or anti-CTLA-4, Abs restored the ex vivo IFN-γ response to BALB/c stimulators. There was no significant difference in IL-2 or IL-4 production between tolerant and rejecting mice, and anti-IL-10 mAbs had no effect on IL-2 or IL-4 production. The Cincinnati cytokine capture assay was used to test whether suppression of IFN-γ production in vivo was also a marker of tolerance. In naive mice, we observed a dramatic increase in serum IFN-γ levels following challenge with allogeneic BALB/c splenocytes or hearts. Tolerant mice challenged with allogeneic BALB/c splenocytes or hearts made significantly less or undetectable amounts of IFN-γ. No IL-4 or IL-10 production was detected in tolerant or rejecting mice. Collectively, our studies suggest that active suppression of IFN-γ production by IL-10 is correlated with, and may contribute to, tolerance induced with intact active bone and anti-CD40 ligand mAbs.