Adoptive Transfer of Renal Allograft Tolerance in a Large Animal Model.

Our recent studies in an inbred swine model demonstrated that both peripheral and intra-graft regulatory cells were required for the adoptive transfer of tolerance to a second, naïve donor-matched kidney. Here, we have asked whether both peripheral and intra-graft regulatory elements are required for adoptive transfer of tolerance when only a long-term tolerant (LTT) kidney is transplanted. Nine highly-inbred swine underwent a tolerance-inducing regimen to prepare LTT kidney grafts which were then transplanted to histocompatible recipients, with or without the peripheral cell populations required for adoptive transfer of tolerance to a naïve kidney. In contrast to our previous studies, tolerance of the LTT kidney transplants alone was achieved without transfer of additional peripheral cells and without strategies to increase the number/potency of regulatory T cells in the donor. This tolerance was systemic, since most subsequent, donor-matched challenge kidney grafts were accepted. These results confirm the presence of a potent tolerance-inducing and/or tolerance-maintaining cell population within LTT renal allografts. They suggest further that additional peripheral tolerance mechanisms, required for adoptive transfer of tolerance to a naïve donor-matched kidney, depend on peripheral cells that, if not transferred with the LTT kidney, require time to develop in the adoptive host.

Abrogation of renal allograft tolerance in MGH miniature swine: the role of intra-graft and peripheral factors in long-term tolerance.

We have previously demonstrated that long-term tolerance (LTT) of an MHC class-I mismatched renal allograft can be achieved with a short course of cyclosporine. In order to examine regulatory mechanisms underlying tolerance in this model, we assessed the contributions of factors within the graft and in the peripheral blood for their relative roles in the maintenance of stable tolerance. Twelve LTT recipients of MHC class-I mismatched primary kidneys were subjected to a treatment consisting of donor-specific transfusion followed by leukapheresis, in order to remove peripheral leukocytes, including putative regulatory T cells (Tregs). Following treatment, 2 controls were followed clinically and 10 animals had the primary graft removed and received a second, donor-MHC-matched kidney. Neither control animal showed evidence of rejection, while 8 of 10 retransplanted animals developed either rejection crisis or full rejection of the second transplant. In vitro assays confirmed that the removed leukocytes were suppressive and that CD4(+) Foxp3(+) Treg reconstitution in blood and kidney grafts correlated with return to normal renal function in animals experiencing transient rejection crises. These data indicate that components of accepted kidney grafts as well as peripheral regulatory components both contribute to the tolerogenic environment required for tolerance of MHC class-I mismatched allotransplants.

The induction of tolerance of renal allografts by adoptive transfer in miniature swine.

Our previous in vitro data have demonstrated that regulatory mechanisms are involved in tolerance of class I-mismatched renal allografts in miniature swine treated with 12 days of high dose Cyclsporin A. In this study, we attempted to induce tolerance of class I-mismatched kidneys by adoptive transfer of cells and/or kidneys from long-term tolerant animals. Fifteen SLA(dd) miniature swine received 1.5 Gy whole body irradiation and class I-mismatched (SLA(gg) ) kidneys from naïve pigs with or without cotransplanted kidneys and/or adoptively transferred cells from long-term tolerant (LTT) SLA(dd) recipients of SLA(gg) grafts. In addition, three SLA(dd) miniature swine received class I mismatched kidney with adoptively transferred cells from LTT SLA(dd) recipients. Naïve kidneys transplanted without a LTT kidney were rejected within 9 days. All recipients of naive kidneys along with cells and kidney grafts from LTT animals showed markedly prolonged survival of the naive renal grafts (day 28, >150 and >150 days). These studies suggest that (1) tolerated kidneys have potent regulatory effects and (2) cells from LTT animals infused in conjunction with kidney grafts augment these regulatory effects. To our knowledge, these studies represent the first demonstration of successful adoptive transfer of tolerance in large animals.

Combined charge and spin density experimental study of the yttrium(III) semiquinonato complex Y(HBPz3)2(DTBSQ) and DFT calculations.

High-resolution X-ray diffraction and polarized neutron diffraction experiments have been performed on the Y-semiquinonate complex, Y(HBPz3)2(DTBSQ), in order to determine the charge and spin densities in the paramagnetic ground state, S = (1/2). The aim of these combined studies is to bring new insights to the antiferromagnetic coupling mechanism between the semiquinonate radical and the rare earth ion in the isomorphous Gd(HBPz3)2(DTBSQ) complex. The experimental charge density at 106 K yields detailed information about the bonding between the Y3+ ion and the semiquinonate ligand; the topological charge of the yttrium atom indicates a transfer of about 1.5 electrons from the radical toward the Y3+ ion in the complex, in agreement with DFT calculations. The electron density deformation map reveals well-resolved oxygen lone pairs with one lobe polarized toward the yttrium atom. The determination of the induced spin density at 1.9 K under an applied magnetic field of 9.5 T permits the visualization of the delocalized magnetic orbital of the radical throughout the entire molecule. The spin is mainly distributed on the oxygen atoms [O1 (0.12(1) mu B), O2(0.11(1) mu B)] and the carbon atoms [C21 (0.24(1) mu B), C22(0.20(1) mu B), C24(0.16(1) mu B), C25(0.12(1) mu B)] of the carbonyl ring. A significant spin delocalization on the yttrium site of 0.08(2) mu B is observed, proving that a direct overlap with the radical magnetic orbital can occur at the rare earth site and lead to antiferromagnetic coupling. The DFT calculations are in good quantitative agreement with the experimental charge density results, but they underestimate the spin delocalization of the oxygen toward the yttrium and the carbon atoms of the carbonyl ring.

Direct observation of finite size effects in chains of antiferromagnetically coupled spins.

Finite spin chains made of few magnetic ions are the ultimate-size structures that can be engineered to perform spin manipulations for quantum information devices. Their spin structure is expected to show finite size effects and its knowledge is of great importance both for fundamental physics and applications. Until now a direct and quantitative measurement of the spatial distribution of the magnetization of such small structures has not been achieved even with the most advanced microscopic techniques. Here we present measurements of the spin density distribution of a finite chain of eight spin-3/2 ions using polarized neutron diffraction. The data reveal edge effects that are a consequence of the finite size and of the parity of the chain and indicate a noncollinear spin arrangement. This is in contrast with the uniform spin distribution observed in the parent closed chain and the collinear arrangement in odd-open chains.

The mass/count distinction: evidence from on-line psycholinguistic performance.

Under the hypothesis that the mass/count distinction in English is marked by a monovalent lexical feature, this article investigates whether features, lexical or morphosyntactic, play a role in simple lexical decision. Research findings have yet to settle how many features are accessed during lexical decision and to what extent morphosyntactic features are computed out of context. We used two on-line lexical decision experiments (simple and morphosyntactic priming). Results show that the lexical feature "mass" is computed in both experiments. However, the morphosyntactic feature "plural" is subject to task-specific effects and surfaces only where operative.

Automated solid-phase synthesis of cyclic peptides bearing a side-chain tail designed for subsequent chemical grafting.

Recent developments in allyl chemistry and palladium solubilization allow automated continuous-flow solid-phase synthesis of cyclic or branched peptides, with specific side-chain cleavage and on-line cyclization. In this paper, we adapted the method to the synthesis of cyclic peptides bearing an anchoring tail on a side chain of the cycle. Side products were obtained with the standard procedure and an additional washing step had to be introduced in the synthesis protocol to remove side products resulting from the palladium allyl cleavage step. The method is illustrated by the automated synthesis of cyclo[-DVal-Arg-Gly-Asp-Glu (-epsilon Ahx-Cys-NH2)-] which contains the Arg-Gly-Asp adhesion motif (RGD) recognized by cellular integrins. The tail of the peptide was designed with a thiol at the carboxylic end to allow subsequent grafting by covalent attachment. Such tailed cyclic peptides can be grafted on different supports for new applications in biomaterial design, cell adhesion assays, affinity chromatography, immunization, vaccine development, ELISA kits, and the building of libraries of conformationally constrained peptides.