Hepatitis C virus core antigen testing in liver and kidney transplant recipients.

HCV RNA levels correlate with the long-term outcome of hepatitis C in liver transplant recipients. Nucleic acid testing (NAT) is usually used to confirm HCV reinfection and to examine viral loads after liver transplantation. HCV core antigen (HCVcoreAg) testing could be an alternative to NAT with some potential advantages including very low intra- and interassay variabilities and lower costs. The performance of HCVcoreAg testing in organ transplant recipients is unknown. We prospectively studied 1011 sera for HCV RNA and HCVcoreAg in a routine real-world setting including 222 samples obtained from patients after liver or kidney transplantation. HCV RNA and HCVcoreAg test results showed a consistency of 98% with a very good correlation in transplanted patients (r > 0.85). The correlation between HCV RNA and HCVcoreAg was higher in sera with high viral loads and in samples from patients with low biochemical disease. Patients treated with tacrolimus showed a better correlation between both parameters than individuals receiving cyclosporine A. HCV RNA/HCVcoreAg ratios did not differ between transplanted and nontransplanted patients, and HCV RNA and HCVcoreAg kinetics were almost identical during the first days after liver transplantation. HCVcoreAg testing can be used to monitor HCV viral loads in patients after organ transplantation. However, the assay is not recommended to monitor antiviral therapies.

Clinical value and safety of liver biopsies in patients transplanted for hepatitis C virus-related end-stage liver disease.

BACKGROUND: Hepatitis C is the leading indication for liver transplantation. Differentiation between recurrent graft hepatitis C (RGH-C) and graft rejection (GR) is challenging. Liver biopsy is standard to diagnose both conditions; however, little information is available regarding this procedure in hepatitis C virus (HCV)-infected liver transplant recipients. METHODS: Liver biopsies (n = 211) from all consecutive patients (n = 138) transplanted for hepatitis C at Hannover Medical School between January 2000 and October 2011 were screened, and a final cohort of 96 patients with 196 biopsies was included. Indications, histopathological findings, and biopsy-related complications were documented. Modifications in the treatment based on the biopsy result and the biochemical outcome were analyzed. RESULTS: Most biopsies (196/211, 93%) were representative. Five patients (2.5%) developed non-fatal biopsy-related complications. Biopsy results were GR (35%), RGH-C (31%), and other diagnoses (34%). GR was independently associated with lower albumin (P = 0.025) and higher bilirubin levels (P = 0.011). Treatment was modified based on the biopsy result in 25% of cases. Alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), and bilirubin levels improved in 41%, 25%, and 31% of cases 4 weeks post biopsy respectively. ALT improvements were more significant in patients with GR than in those with RGH-C. CONCLUSION: Liver biopsy in HCV-infected liver transplant recipients is safe and representative in >90% of cases. GR is independently associated with lower albumin and higher bilirubin levels.

Enrichment of regulatory T cells in acutely rejected human liver allografts.

Acute cellular rejection (ACR) occurs frequently after liver transplantation and can usually be controlled. Triggering of allospecific immune responses and lack of immunoregulation are currently suggested as a cause of ACR, but there are no investigations of intrahepatic immune responses during ACR. Therefore we prospectively analyzed the intrahepatic T cell infiltration pattern in correlation to the severity of ACR in a cohort of patients with graft hepatitis (n = 151). While CD4(+) cells dominated the portal infiltrates in mild-moderate ACR, CD8(+) cells prevailed in severe ACR. Furthermore portal CD8(+) and not CD4(+) infiltration correlated with serum transaminases and with the likelihood of subsequent ACRs. Surprisingly, the rise of portal effector T cells density during ACR was surpassed by the increase in portal infiltration of regulatory T cells by a factor of two. Thus ACRs rather showed an increase and not a lack of regulation, as was suggested by analysis of peripheral blood mononuclear cells. Despite the pattern of enhanced immunoregulation, patients with severe ACR had a higher risk for subsequent rejections and showed a trend to a reduced survival. Thus, patients with severe rejections might need a modification of their immunosuppression to improve prognosis.

Interleukin 7 induces CD4+ T cell-dependent tumor rejection.

The potential of interleukin 7 (IL-7) to induce an antitumor response in vivo was analyzed. Therefore, the IL-7 gene was expressed in the plasmacytoma cell line J558L. Although the growth of IL-7-producing cells was not retarded in vitro, the IL-7-producing cells were completely rejected upon injection into mice. Tumor rejection was observed only in syngeneic but not in nude mice. The tumor-suppressive effect could be abolished by the parallel injection of an anti-IL-7 monoclonal antibody. Immunohistochemical analysis revealed IL-7-dependent infiltration of the tumor tissue by CD4+ and CD8+ T lymphocytes, and also type 3 complement receptor-positive (CR3+) cells, predominantly macrophages. Depletion of T cell subsets in tumor-bearing mice showed the absolute dependence of the antitumor response on CD4+ cells, whereas tumor rejection was unaffected by depletion of CD8+ cells. In addition to CD4+ cells, CR3+ cells were also needed for tumor rejection. The antitumor effect of IL-7 was confirmed by expression of the IL-7 gene in a second tumor cell line of different cellular origin. Together, our results demonstrate that a high local IL-7 concentration at the tumor site obtained by tumor cell-targeted gene transfer leads to tumor rejection involving a cellular mechanism that seems to be different from the ones observed in analogous experiments with other cytokines.

Expression of tumor necrosis factor by different tumor cell lines results either in tumor suppression or augmented metastasis.

Tumor necrosis factor (TNF) produced by tumor cells after gene transfer can effectively suppress the growth of locally growing tumors. We wanted to test the effects of "local" TNF on the growth of a highly metastatic cell line. Therefore, a recombinant retrovirus allowing expression of the TNF gene by the beta-actin promotor has been constructed and used to infect the two tumor cell lines EB and ESB, which grow as solid tumor or metastasize, respectively. Expression of TNF by EB cells resulted in their rapid and dose-dependent rejection. In sharp contrast, mice injected with ESB cells producing similar amounts of TNF showed no signs of tumor suppression, but rather had reduced survival rates that correlated with enhanced hepatic metastases. The accelerated formation of liver metastases by ESB TNF cells could be reversed by an anti-TNF mAb. These results demonstrate the opposite effects TNF may have on tumor growth: suppression of a locally growing tumor and promotion of metastasis formation.

[CMV-enterocolitis as a cause for repeated intestinal intussusceptions in an adult patient after liver transplantation?]. / CMV-Enterokolitis bei einer erwachsenen lebertransplantierten Patientin als Ursache rezidivierender Invaginationen?

Intestinal intussusception in the adult is often idiopathic but also known to be associated with chronic inflammatory bowel disease, coeliac disease, tumours or previous abdominal operations. A 22-year-old women after liver transplantation due to Crigler Najar Syndrome suffered from repeated episodes of abdominal pain. The diagnosis of repeated self-limited intestinal intussusceptions was made by computed tomography and ultrasonography. A laparoscopy revealed no cause for the intussusceptions. During a new episode of abdominal pain caused again by an intussusception a colonoscopy was performed that showed aspects of a discreet colitis. In the biopsies CMV was detected by qualitative PCR, while blood tests for CMV pp65 antigen were negative. A therapy with gancyclovir was initiated which lead to remission of the patient's symptoms. A colonoscopy six weeks later showed a completely normal colon, while in the biopsies CMV was not detectable. After a follow-up of one year the patient has not suffered from any further episodes. This case demonstrates the role of chronic intestinal CMV infection as a possible causative factor for repeated intussusceptions in immunosuppressed patients. Whenever possible a PCR for CMV in colon biopsies should be carried out to detect an intestinal CMV infection because as shown in our case results for immunohistopathology and CMV pp65 can be negative despite a chronic infection.

Fulminant hepatic failure due to chemotherapy-induced hepatitis B reactivation: role of rituximab.

Hepatitis B virus reactivation during immunosuppressive therapies can lead to liver failure with very limited treatment options available. We report here on two cases of severe hepatitis B reactivation during chemotherapy including rituximab for B cell lymphoma which were treated with liver or liver-cell transplantation. Liver function was normal and HBV infection was unknown in both patients before chemotherapy was started. Impaired liver function became apparent after 4 and 6 courses of chemotherapy, respectively, and both patients experienced fulminant hepatic failure despite antiviral treatment with lamivudine or entecavir. Patient A underwent liver transplantation after documentation of complete remission of the lymphoma and survived without any evidence for hepatitis B recurrence. Patient B received 4 courses of hepatocyte transplantation but did not survive. These cases underline the importance of anti-HBc screening in patients receiving immunosuppressive treatments in particular when rituximab is given. Pre-emptive antiviral treatments should be administered since delayed antiviral treatment is frequently unable to prevent liver failure.

Comparison of outcomes of peritoneal dialysis catheters placed by the fluoroscopically guided percutaneous method versus directly visualized surgical method.

PURPOSE: To compare complications in catheters placed by the fluoroscopically guided percutaneous method versus directly visualized surgery. MATERIALS AND METHODS: A retrospective cohort analysis was performed. Mechanical complication rate data, including catheter leakage, malfunction, malposition, and bleeding, were compared between the two groups over a 1-year follow-up period. Additionally, exit site infection rates, tunnel infection rates, and peritonitis episodes were evaluated based on the incidence within 30 days of insertion and 30 days to 1 year after insertion. RESULTS: A total of 101 patients were analyzed (52 in the fluoroscopic guidance group, 49 in the direct visualization group). Prevalence of diabetes was similar: 56% in the directly visualized surgery group and 47% in the fluoroscopically guided treatment group (P = .37). Although the difference was not significant, complication rates tended to be higher in the directly visualized surgery group compared with the percutaneous placement group. These included catheter leakage (13% vs 4%; P = .093), malfunction (11% vs 9%; P = .73), malposition (13% vs 6%; P = .20), and bleeding (8% vs 2%; P = .21). There were no differences in early and late exit site infections and tunnel infections. Late peritonitis rates were lower in the percutaneous placement group (20%) than in the direct visualization group (42%) (P = .018). Diabetic patients had approximately six times greater risk of catheter malfunction than nondiabetic patients regardless of method of catheter insertion. CONCLUSIONS: Placement of peritoneal dialysis catheters percutaneously with fluoroscopic guidance is as safe as placement with direct visualization techniques.

Neurologic complications after allogeneic hematopoietic stem cell transplantation: risk factors and impact.

Neurologic complications (NCs) may be a significant source of morbidity and mortality after hematopoietic cell transplantation (HCT). We performed a retrospective study of 263 consecutive patients undergoing allogeneic HCT for hematological malignancies to determine the incidence, risk factors and clinical impact of NCs in the first 5 years after HCT. We determined the incidence of central nervous system (CNS) infection, intracranial hemorrhage, ischemic stroke, metabolic encephalopathy, posterior reversal encephalopathy syndrome, seizure and peripheral neuropathy. In all, 50 patients experienced 63 NCs-37 early (⩽day +100), 21 late (day +101 to 2 years) and 5 very late (2 to 5 years). The 1- and 5-year cumulative incidences of all NCs were 15.6% and 19.2%, respectively, and of CNS complication (CNSC; all of the above complications except peripheral neuropathy) were 12.2 and 14.5%. Risk factors for CNSC were age (hazard ratio (HR)=1.06 per year, P=0.0034), development of acute GvHD grade III-IV (HR=2.78, P=0.041), transfusion-dependent thrombocytopenia (HR=3.07, P=0.025) and delayed platelet engraftment (>90th centile; HR=2.77, P=0.043). CNSCs negatively impacted progression-free survival (HR=2.29, P=0.0001), overall survival (HR=2.63, P<0.0001) and non-relapse mortality (HR=8.51, P<0.0001). NCs after HCT are associated with poor outcomes, and usually occur early after HCT.

Vaccinations with tumor cells genetically engineered to produce different cytokines: effectivity not superior to a classical adjuvant.

The potential of tumor cells (J558L) engineered to produce one of 5 different cytokines (interleukin 2, interleukin 4, interleukin 7, tumor necrosis factor, or gamma-interferon) to give rise to systemic immunity protective against a contralateral challenge with the parental cells was analyzed. The rejection of all cytokine-producing cells appeared to induce some systemic response capable of mediating the rejection of low numbers of subsequently contralaterally injected cells, but the effect was much less obvious with higher cell numbers. The injection of any possible combination of two of the cytokine producers did not reveal any synergistic effects. The cytokine gene-transfected tumor cells were not superior to the parental cells admixed with the adjuvant Corynebacterium parvum with respect to their potential as immunogens to induce immunity.

A sialyl-Le(x)-negative melanoma cell line binds to E-selectin but not to P-selectin.

The adhesion molecules E-selectin (ELAM-1) and P-selectin (GMP-140/CD62) recognize the carbohydrate motives sialyl-Le(x), sialyl-diLe(x), or sialyl-Lea, though with different affinity. We found that the melanoma cell line NKI-4 bound to E-selectin, but not to P-selectin. This melanoma cell line did not express sialyl-Le(x), but was positive for sialyl-diLe(x) and sialyl-Le(a). In contrast, 2 other melanoma cell lines, MeWo and SK-MEL-28, expressing either sialyl-diLe(x) or sialyl-Le(a) on the cell surface, bound neither E-selectin nor P-selectin. Transfection of the fucosyltransferases Fuc-TIII, Fuc-TIV, and Fuc-TV mediates cell surface expression of sialyl-Le(x) in many cell lines. We detected transcripts of the fucosyltransferases Fuc-TIII and Fuc-TV in 4 melanoma cell lines despite the absence of cell surface sialyl-Le(x). Our observations indicate that expression of fucosyltransferases (Fuc-TIII and -TV) and generation of cell-surface sialyl-diLe(x) are not sufficient to permit adherence to E-selectin or P-selectin. Furthermore, it seems possible that a yet undefined ligand different from sialyl-Le(x), sialyl-diLe(x), or sialyl-Le(a) enables melanoma cells to adhere to E-selectin.

Chimeric interleukin 2 receptor alpha chain antibody derivatives with fused mu and gamma chains permit improved recruitment of effector functions.

In order to investigate the feasibility of shuffling effector functions of monoclonal antibodies, we constructed chimeric antibodies with fused heavy chains. The derivatives studied are based on a monoclonal antibody directed against the alpha chain of the human Il2-R. Derivatives studied were the IgG1 and IgM isotypes; IgM delta, lacking the ability of multimerization due to a deletion; IgMc gamma 1 and IgGlc mu, with fused mu and gamma 1 chains and vice versa. IgG1, IgM delta and IgMc gamma 1 were secreted as monomers, IgM and IgG1c mu as polymers. The Ki values for competition with radio-iodinated Il2 with respect to binding to the Il2-R were markedly lower for polymeric than for monomeric derivatives (300-400 pM versus 2500-6500 pM). Recruitment of complement mediated by the deposition of C3 fragments, either of heterologous (rabbit) or homologous (human) origin, was mediated only by the polymeric derivatives IgM and IgG1c mu. ADCC was mediated by monomeric IgG1 and polymeric IgG1c mu, the latter derivative being active at concentrations 100-fold lower than the former. Together, the results demonstrate that both CDC and ADCC effector functions can be combined on a polymeric antibody derivative with fused gamma 1 and mu chains. In addition, such a derivative, due to its polymeric nature, has a high binding affinity. These properties may be important for the elimination of target cells in vivo.

Synthesis and functional characterization of a recombinant monoclonal antibody directed against the alpha-chain of the human interleukin-2 receptor.

We have determined the sequence of the light and heavy chains of mAb 3G-10 (IgG1), a monoclonal antibody competing with interleukin 2 (IL2) for binding to the human IL2 receptor Tac protein. The antibody-encoding genes were chimerized by introducing splice donor and part of the intron sequences into the cDNA and subsequently linking it to the constant parts of the human IgG1 gene. The chimeric mAb was produced in mouse myeloma cells and purified. Murine and chimeric mAbs showed similar properties with respect to inhibition of T-cell proliferation. In contrast to its murine counterpart, the chimeric mAb exhibited Ab-dependent cellular cytotoxicity and, when combined with an Ab recognizing a different epitope on the IL2 receptor Tac protein, was able to activate human complement. The chimerized mAb might therefore have improved therapeutic efficacy.

T cells bind to the endothelial adhesion molecule GMP-140 (P-selectin).

A crucial step in an effective immune response is the adhesion of circulating lymphocytes. Lymphocytes must attach to endothelial cells before they can migrate into the graft. It has been shown that T cells bind to ICAM-1 and VCAM-1. Additionally, certain T cell subsets bind to ELAM-1. We now report that resting CD4+ and CD8+ T cells as well as individual CD4+ T cell clones and CD8+ T cell lines bind to GMP-140 in an adhesion assay using protein chimeras consisting of the extracellular domain of GMP-140 linked to the hinge domain of human IgG1. Whereas resting T cells bound similarly to ELAM-1 IgG and GMP-140 IgG, activated T cells represented by CD4+ T cell clones and CD8+ T cell lines bound to GMP-140 IgG, but not to ELAM-1 IgG. Neither the binding to immobilized GMP-140 IgG, nor to immobilized ELAM-1 IgG could provide T cells with costimulatory signals for proliferation in the presence of submitogenic concentrations of anti-CD3 antibodies. The binding of T cells to the endothelial adhesion receptor GMP-140 might be important during the initial adhesion process of lymphocytes in rejecting grafts.

Bistability and hysteresis in the organization of apparent motion patterns.

In a paradigm for which 2 distinct patterns are perceived for the same stimulus, perceptual hysteresis (persistence of a percept despite parameter change to values favoring the alternative pattern) and temporal stability (persistence despite intrinsic propensities toward spontaneous change) are interdependent. Greater persistence during parameter change reduces temporal stability, slowing the rate of parameter change reduces hysteresis by increasing opportunity for spontaneous change, and increasing temporal stability (by enlarging the stimulus) increases hysteresis. Hysteresis results in the perception of parametrically disfavored patterns; a parameter can influence a percept without specifying it. The visual system thus exhibits time-dependent behavior analogous to dynamical behavior observed in other systems, both physical and biological, for which there is competition among alternative patterns that vary in relative stability.

Context effects on perceived position: sustained and transient temporal influences on spatial interactions.

The effects of sustained and transient responses to inducing lines on the perceived position of nearby test lines were measured as constant errors in the vernier alignment of the test lines. The sustained response to the continued presence of the inducing lines had no effect on the perceived position of the test lines for very small inducing/test-line distances, and a repulsive effect for larger distances. Transient responses to the onset of the inducing lines had attractive effects for small distances, whereas transient responses to the offset of the inducing lines had repulsive effects for all distances tested. Attraction and repulsion effects on perceived position are accounted for by facilitating and inhibiting interactions that influence the relative sensitivities of an ensemble of position-selective detecting units.

The effect of attentional spread on spatial resolution.

The effects of attentional spread were studied by having subjects detect a luminance increment along a row of evenly spaced dots. The increment could occur for the central, fixated dot (Narrow Attention) or for either the fixation dot or one of the four dots to its left or right (Broad Attention). Narrow Attention enhanced the detection of luminance increments for the fixated dot, and also enhanced spatial resolution near the fixation dot for judgments of vernier alignment and separation. This indicated that the sensitivity of small spatial filters in the fovea was increased more by narrowly focused than broadly spread attention. Effects of attentional spread on spatial resolution were not obtained for judgments of the separation between two peripherally located targets, perhaps because of their dependence on eccentricity (position) rather than separation.

Spatial scale dependent in-phase and anti-phase directional biases in the perception of self-organized motion patterns.

A long row of evenly spaced dots is displaced on successive frames by half the distance between the dots. Although these stimuli are directionally ambiguous, spatially and temporally coherent unidirectional and oscillatory motion patterns are perceived as a result of the temporal persistence of competing in-phase and anti-phase directional biases, respectively. The perceiver's spatial scale is critical is determining whether dots are near enough to favor an in-phase bias or far enough apart to favor an anti-phase bias. The results are explained by a differential-gradient model of cooperative interaction, which specifies that the strength of facilitating (excitatory) interactions among motion detectors with similar directional selectivity falls off with distance at a greater rate than the strength of competing inhibiting interactions.

Perceptual stability and the selective adaptation of perceived and unperceived motion directions.

Adaptation was studied in a paradigm in which the adapting stimulus was a variably biased version of a bistable apparent motion stimulus, a motion quartet, and the post-adaptation test stimulus was a "neutral" motion quartet. Either horizontal or vertical motion was perceived, never both at the same time. When only one of these was perceived during the entire adaptation phase of a trial, and the perceived motion was highly stable, adaptation effects were greater for the perceived than the unperceived motion directions (i.e., adaptation was selective to the perceived motion). However, when the perceived motion during adaptation was relatively unstable (i.e., when the perceived motion was more likely to spontaneously change directions), similar levels of adaptation were obtained for perceived as well as unperceived, but possible motion directions. Thus, adaptation occurs prior to the determination of which of the competing motion directions will be perceived. The relationship between the stability of the adapting percept and the selectivity of adaptation is explained in terms of differences in the activation of mutually inhibitory horizontal and vertical motion detectors.

Attentional control of spatial scale: effects on self-organized motion patterns.

Prior to the presentation of a test stimulus, subjects' attentional state was either narrowly focused on a particular location or broadly spread over a large spatial region. In previous studies, it was found that broadly spread attention enhances the sensitivity of relatively large spatial filters (increasing the perceiver's spatial scale), thereby diminishing spatial resolution and enhancing sensitivity to global stimulus structure. In this study it is shown that attentional spread also affects the self-organization of unidirectional versus oscillatory motion patterns for the directionally ambiguous, counterphase presentation of rows of evenly-spaced visual elements (lines segments; dots); i.e. qualitatively different motion patterns can be formed for the same stimulus at different spatial scales. Although the degree to which attention is spread along a spatial axis can be controlled by the perceiver, the effects of spread attention are not limited to a single axis. These results, as well as previously observed effects of attentional spread on spatial resolution, are accounted for by a neural model involving large, foveally-centered receptive fields with co-operatively interacting subunits (probably at the level of MST or higher).