Persistence of Indirect but Not Direct T Cell Xenoresponses in Baboon Recipients of Pig Cell and Organ Transplants.

We investigated the contributions of direct and indirect T cell antigen recognition pathways to the immune response to porcine antigens in naïve baboons and baboon recipients of pig xenografts. In naïve baboons, in vitro culture of peripheral blood T cells with intact pig cells (direct xenorecognition pathway) or pig cell sonicates and baboon antigen-presenting cells (indirect xenorecognition pathway) induced the activation and expansion of xenoreactive T cells producing proinflammatory cytokines, interleukin-2 and interferon-γ. Primary indirect xenoresponses were mediated by preexisting memory T cells, whose presence is not typically observed in primary alloresponses. Next, baboons were conditioned with a nonmyeloablative regimen before short-term immunosuppression and transplantation of xenogeneic peripheral blood progenitor cells and a kidney, heart, or pancreatic islets from a miniature swine. All transplants were rejected acutely within 30 days after their placement. Posttransplantation, we observed an inhibition of the direct xenoresponse but a significant expansion of indirectly activated proinflammatory T cells. These results suggest that additional treatment to suppress indirect T cell immunity in primates may be required to achieve tolerance of pig xenografts through hematopoietic chimerism.

TIDILAP: Treatment of iron deficiency in lipoprotein apheresis patients --A prospective observational multi-center cohort study comparing efficacy, safety and tolerability of ferric gluconate with ferric carboxymaltose.

OBJECTIVES: Iron deficiency (ID) and iron deficiency anemia (IDA) are common findings in patients undergoing lipoprotein apheresis (LA). Different intravenous (iv) formulations are used to treat ID in LA patients, however guidelines and data on ID/IDA management in LA patients are lacking. We therefore performed a prospective observational multi-center cohort study of ID/IDA in LA patients, comparing two approved i.v. iron formulations, ferric gluconate (FG) and ferric carboxymaltose (FCM). METHODS: Inclusion criteria were a) serum ferritin <100 µg/L or b) serum ferritin <300 µg/L and transferrin saturation <20%. Patients received either FG (62.5 mg weekly) or FCM (500 mg once in ID or up to 1000 mg if IDA was present) i.v. until iron deficiency was resolved. Efficacy and safety were determined by repeated laboratory and clinical assessment. Iron parameters pre and post apheresis were measured to better understand the pathogenesis of ID/IDA in LA patients. RESULTS: 80% of LA patients treated at the three participating centers presented with ID/IDA; 129 patients were included in the study. Serum ferritin and transferrin levels were reduced following apheresis (by 18% (p < 0.0001) and by 13% (p < 0.0001) respectively). Both FG and FCM were effective and well tolerated in the treatment of ID/IDA in LA patients. FCM led to a quicker repletion of iron stores (p < 0.05), while improvement of ID/IDA symptoms was not different. Number and severity of adverse events did not differ between FG and FCM, no severe adverse events occurred. CONCLUSIONS: Our results suggest that FG and FCM are equally safe, well-tolerated and effective in treating ID/IDA in LA patients. These data form the basis for follow-up randomized controlled trials to establish clinical guidelines.

[Axon-reflex based nerve fiber function assessment in the detection of autonomic neuropathy]. / Axon-Reflex-basierte Nervenmessverfahren in der Diagnostik autonomer Neuropathie.

Axon-reflex-based tests of peripheral small nerve fiber function including techniques to quantify vasomotor and sudomotor responses following acetylcholine iontophoresis are used in the assessment of autonomic neuropathy. However, the established axon-reflex-based techniques, laser Doppler flowmetry (LDF) to assess vasomotor function and quantitative sudomotor axon-reflex test (QSART) to measure sudomotor function, are limited by technically demanding settings as well as interindividual variability and are therefore restricted to specialized clinical centers. New axon-reflex tests are characterized by quantification of axon responses with both temporal and spatial resolution and include "laser Doppler imaging (LDI) axon-reflex flare area test" to assess vasomotor function, the quantitative direct and indirect test of sudomotor function (QDIRT) to quantify sudomotor function, as well as the quantitative pilomotor axon-reflex test (QPART), a technique to measure pilomotor nerve fiber function using adrenergic cutaneous stimulation through phenylephrine iontophoresis. The effectiveness of new axon-reflex tests in the assessment of neuropathy is currently being investigated in clinical studies.

[Autonomic neuropathies]. / Formen autonomer nervenkrankheiten.

Autonomic neuropathies are a heterogeneous group of diseases that involve damage of small peripheral autonomic Aδ- and C-fibers. Causes of autonomic nerve fiber damage are disorders such as diabetes mellitus and HIV-infection. Predominant symptoms of autonomic neuropathy are orthostatic hypotension, gastro-intestinal problems, urogenital dysfunction, and cardiac arrhythmia, which can severely impair the quality of life in affected patients. Furthermore, autonomic neuropathies can be induced by autoimmune diseases such as acute inflammatory demyelinating polyneuropathy, hereditary disorders such as the lysosomal storage disorder Fabry disease and hereditary sensory and autonomic neuropathies, as well as certain toxins and drugs.

[Autonomic neuropathies--diagnosis and evidence based treatment]. / Autonome nervenkrankheiten--früherkennung und leitliniengerechte behandlung.

Among the few well-established techniques to diagnose autonomic dysfunction are head-up-tilt table testing, heart rate variability measurement and axon-reflex based sudomotor testing. Recent research focused on the development of novel techniques to assess autonomic function based on axon-reflex testing in both vasomotor and pilomotor nerve fibers. However, these techniques are clinically not widely used due to technical limitations and the lack of data on their utility to detect autonomic dysfunction in patients with neuropathy. The treatment of autonomic neuropathies should focus on the management of the underlying disease. In addition, symptomatic treatment of autonomic dysfunction should be provided in an individual patient-centered multimodal regimen that may incorporate both pharmacological and non-pharmacological strategies. The use of medication in autonomic dysfunction requires a careful risk-benefit assessment and should be individually adjusted based on both therapeutic success and occurrence of adverse effects.

Induction of T-cell response to cryptic MHC determinants during allograft rejection.

The presentation of MHC peptides by recipient and donor antigen presenting cells is an essential element in allorecognition and allograft rejection. MHC proteins contains two sets of determinants: the dominant determinants that are efficiently processed and presented to T cells, and the cryptic determinants that are not presented sufficiently enough to induce T-cell responses in vivo. In transplanted mice, initial T-cell response to MHC peptides is consistently limited to a single or a few immunodominant determinants on donor MHC molecule. However, in this article we show that under appropriate circumstances the hierarchy of determinants on MHC molecules can be disrupted. First, we observed that gamma IFN can trigger de novo presentation of cryptic self-MHC peptides by spleen cells. Moreover, we showed that allotransplantation is associated with induction of T-cell responses to formerly cryptic determinants on both syngeneic and allogeneic MHC molecules. Our results suggest that cross-reactivity and inflammation are responsible for the initiation of these auto- and alloimmune responses after transplantation.