Immune reconstitution/immunocompetence in recipients of kidney plus hematopoietic stem/facilitating cell transplants.

Nineteen subjects have more than 18 months' follow-up in a phase IIb tolerance protocol in HLA-mismatched recipients of living donor kidney plus facilitating cell enriched hematopoietic stem cell allografts (FCRx). Reduced intensity conditioning preceded a kidney allograft, followed the next day by FCRx. Twelve have achieved stable donor chimerism and have been successfully taken off immunosuppression (IS).

The need for inducing tolerance in vascularized composite allotransplantation.

Successful hand and face transplantation in the last decade has firmly established the field of vascularized composite allotransplantation (VCA). The experience in VCA has thus far been very similar to solid organ transplantation in terms of the morbidity associated with long-term immunosuppression. The unique immunological features of VCA such as split tolerance and resistance to chronic rejection are being investigated.

Simultaneous bone marrow and composite tissue transplantation in rats treated with nonmyeloablative conditioning promotes tolerance.

Background: Approaches to safely induce tolerance in vascularized composite allotransplantation (VCA) with chimerism through bone marrow transplantation (BMT) are currently being pursued. However, VCA was historically performed sequentially after donor chimerism was established. Delayed VCA is not clinically applicable due to the time constraints associated with procurement from deceased donors.

Tolerance induction in HLA disparate living donor kidney transplantation by donor stem cell infusion: durable chimerism predicts outcome.

Background: We recently reported that durable chimerism can be safely established in mismatched kidney recipients through nonmyeloablative conditioning followed by infusion of a facilitating cell (FC)-based hematopoietic stem cell transplantation termed FCRx. Here we provide intermediate-term follow-up on this phase II trial.

Methods: Fifteen human leukocyte antigen-mismatched living donor renal transplant recipients underwent low-intensity conditioning (fludarabine, cyclophosphamide, 200 cGy TBI), received a living donor kidney transplant on day 0, then infusion of cryopreserved FCRx on day +1.

A critical role for the TLR4/TRIF pathway in allogeneic hematopoietic cell rejection by innate immune cells.

We show for the first time that signaling through the TLR4/TRIF pathway plays a critical role in allogeneic bone marrow cell (BMC) rejection. This appears to be unique to BMCs as organ allografts are rejected mainly via MyD88 signaling. Using T- or T-/B-cell-deficient mice, we found that BMC allorejection occurred early before T-cell activation and was T- and B-cell independent, suggesting an effector role for innate immune cells in BMC rejection.

Innate and adaptive immune responses are tolerized in chimeras prepared with nonmyeloablative conditioning.

Background: Mixed chimerism is an effective approach for tolerance induction in transplantation. Strategies to achieve mixed chimerism with relatively low toxicity have significantly expanded the clinical use of chimerism.

Methods: Allogeneic bone marrow transplants were performed between B6 (H2(b)) and BALB/c (H2(d)) mice.

Differential outcomes in prediabetic vs. overtly diabetic NOD mice nonmyeloablatively conditioned with costimulatory blockade.

Objective: Autoimmune diabetes can be reversed with mixed chimerism. However, the myelotoxic agents currently required to establish chimerism have prevented the translation of this approach to the clinic. Here, we investigated whether multimodal costimulatory blockade would enhance chimerism and promote islet allograft tolerance in spontaneously diabetic nonobese diabetic (NOD) mice.

Evidence that FoxP3+ regulatory T cells may play a role in promoting long-term acceptance of composite tissue allotransplants.

Background: FoxP3/CD4/CD25 regulatory T cells (Treg) play an important role in maintaining peripheral tolerance and are potent suppressors of T-cell activation. In this study, we evaluated the role of Treg in peripheral tolerance to composite tissue allografts (CTA).

Methods: Mixed allogeneic chimeric rats were prepared by preconditioning recipients with anti-αβ-T-cell receptor monoclonal antibody followed by total body irradiation.

CD8α+ plasmacytoid precursor DCs induce antigen-specific regulatory T cells that enhance HSC engraftment in vivo.

CD8-positive/T-cell receptor-negative (CD8(+)/TCR(-)) graft facilitating cells (FCs) are a novel cell population in bone marrow that potently enhance engraftment of hemopoietic stem cells (HSCs). Previously, we showed that the CD11c(+)/B220(+)/CD11b(-) plasmacytoid-precursor dendritic cell (p-preDC) FC subpopulation plays a critical but nonredundant role in facilitation. In the present study, we investigated the mechanism of FC function.

Plasmacytoid precursor dendritic cells from NOD mice exhibit impaired function: are they a component of diabetes pathogenesis?

Objective: Plasmacytoid precursor dendritic cell facilitating cells (p-preDC FCs) play a critical role in facilitation of syngeneic and allogeneic hematopoietic stem cell (HSC) engraftment. Here, we evaluated the phenotype and function of CD8(+)/TCR(-) FCs from NOD mice.

Research Design And Methods: The phenotype of CD8(+)/TCR(-) FCs was analyzed by flow cytometry using sorted FCs from NOD, NOR, or B6 mice.

Past, present, and future prospects for inducing donor-specific transplantation tolerance for composite tissue allotransplantation.

Composite tissue allotransplantation (CTA) is among the most immunologically complex and newest transplant fields. Although the field has made considerable advances, there are still concerns that these procedures are performed to enhance quality-of-life issues and are not lifesaving procedures that restore physiologic function. Two challenges limit the widespread application of CTA; the first is chronic rejection, the most prevailing cause of organ allograft failure after transplantation; the second barrier is the numerous health complications associated with lifelong immunosuppressive therapy.

Plasma membrane Ca(2+) -ATPase associates with CLP36, alpha-actinin and actin in human platelets.

The plasma membrane Ca(2+)-ATPase (PMCA) plays an essential role in maintaining low cytosolic Ca(2+) in resting platelets. Earlier studies demonstrated that the 4b isoform of PMCA interacts via its C-terminal end with the PDZ domains of membrane-associated guanylate kinase proteins. Activation of saponin-permeabilized platelets in the presence of a peptide composed of the last ten residues of the PMCA4b C-terminus leads to a significant decrease of PMCA associated with the cytoskeleton, suggesting that PDZ domain interactions play a role in tethering the pump to the cytoskeleton.

The influence of SRC-family tyrosine kinases on Na,K-ATPase activity in lens epithelium.

Purpose: Na,K-adenosine triphosphatase (ATPase) is essential for the regulation of cytoplasmic ion concentrations in lens cells. Earlier studies demonstrated that tyrosine phosphorylation by Lyn kinase, a Src-family member, inhibits Na,K-ATPase activity in porcine lens epithelium. In the present study, experiments were conducted to compare the ability of other Src-family kinases (Fyn, Src, and Lck) and Fes, a non-Src-family tyrosine kinase, to alter Na,K-ATPase activity.

The influence of protein tyrosine phosphatase-1B on Na,K-ATPase activity in lens.

The abnormal sodium content of many cataracts suggests Na,K-ATPase is vital for maintenance of eye lens transparency. Since tyrosine phosphorylation is considered a possible regulatory mechanism for Na,K-ATPase, experiments were conducted to test the influence of protein tyrosine phosphatase-1B (PTP-1B) on Na,K-ATPase activity. Membrane material was isolated separately from porcine lens epithelium and fiber cells.

The influence of Lyn kinase on Na,K-ATPase in porcine lens epithelium.

Na,K-ATPase is essential for the regulation of cytoplasmic Na+ and K+ levels in lens cells. Studies on the intact lens suggest activation of tyrosine kinases may inhibit Na,K-ATPase function. Here, we tested the influence of Lyn kinase, a Src-family member, on tyrosine phosphorylation and Na,K-ATPase activity in membrane material isolated from porcine lens epithelium.