Rhizobium meliloti produces a family of sulfated lipooligosaccharides exhibiting different degrees of plant host specificity.

We have shown that a Rhizobium meliloti strain overexpressing nodulation genes excreted high amounts of a family of N-acylated and 6-O-sulfated N-acetyl-beta-1,4-D-glucosamine penta-, tetra-, and trisaccharide Nod factors. Either a C(16:2) or a C(16:3) acyl chain is attached to the nonreducing end subunit, whereas the sulfate group is bound to the reducing glucosamine. One of the tetrasaccharides is identical to the previously described NodRm-1 factor. The two pentasaccharides as well as NodRm-1 were purified and tested for biological activity. In the root hair deformation assay the pentasaccharides show similar activities on the host plants Medicago sativa and Melilotus albus and on the non-host plant Vicia sativa at a dilution of up to 0.01-0.001 microM, in contrast to NodRm-1, which displays a much higher specific activity for Medicago and Melilotus than for Vicia. The active concentration range of the pentasaccharides is more narrow on Medicago than on Melilotus and Vicia. In addition to root hair deformation, the different Nod factors were shown to induce nodule formation on M. sativa. We suggest that the production of a series of active signal molecules with different degrees of specificity might be important in controlling the symbiosis of R. meliloti with several different host plants or under different environmental conditions.     

Pre-B acute lymphoblastic leukemia cells may induce T-cell anergy to alloantigen

Even if neoplastic cells express tumor associated antigens they still may fail to function as antigen presenting cells (APC) if they lack expression of one or more molecules critical for the induction of productive immunity. These cellular defects can be repaired by physiologic activation, transfection, or fusion of tumor cells with professional APC. Although such defects can be repaired, antitumor specific T cells may still fail to respond in vivo if they may have been tolerized. Here, human pre-B cell acute lymphoblastic leukemia (pre-B ALL) was used as a model to determine if primary human tumor cells can function as alloantigen presenting cells (alloAPC) or alternatively whether they induce anergy. In the present report, we show that pre-B cell ALL express alloantigen and adhesion molecules but uniformly lack B7-1 (CD80) and only a subset express B7-2 (CD86). Pre-B ALL cells are inefficient or ineffective alloAPC and those cases that lack expression of B7-1 and B7-2 also induce alloantigen specific T- cell unresponsiveness. Under these circumstances, T-cell unresponsiveness could be prevented by physiologic activation of tumor cells via CD40, cross-linking CD28, or signaling through the common gamma chain of the interleukin-2 receptor on T cells. Taken together, these results suggest that pre-B ALL may be incapable of inducing clinically significant T-cell-mediated antileukemia responses. This defect may be not only due to their inability to function as APC, but also due to their potential to induce tolerance. Attempts to induce clinically significant antitumor immune responses may then require not only mechanisms to repair the antigen presenting capacity of the tumor cells, but also reversal of tolerance.     

The severe combined immunodeficient-human peripheral blood stem cell (SCID-huPBSC) mouse: a xenotransplant model for huPBSC-initiated hematopoiesis

Mononuclear cells (MNCs) containing peripheral blood stem cells (PBSCs) were obtained from solid-tumor patients undergoing mobilizing chemotherapy followed by granulocyte colony-stimulating factor for PBSC transplantation-supported dose-intensified anticancer chemotherapy and were transplanted into unconditioned "nonleaky" young severe combined immunodeficient mice. Multilineage engraftment was shown by flow cytometry and immunocytochemistry using monoclonal antibodies to various human cell surface antigens as well as identification of human immunoglobulin in murine sera. Within a dose range of MNCs suitable for transplantation (10 to 36 x 10(6) cells/graft) the number of CD34+ cells injected (optimal at > 0.7 x 10(6)/graft) determined the yield of human cells produced in recipient animals. Engraftment of hu PBSC preparations resulted in prolonged generation of physiologic levels of human cytokines including interleukin-3 (IL-3), IL-6, and granulocyte- macrophage colony-stimulating factor, which were detectable in the murine blood over a period of at least 4 months. In vivo survival of immature human progenitor cells was preserved even 9 months after transplantation. Because human IL-3 is known to stimulate early hematopoiesis, a rat fibroblast cell line was stably transfected with a retroviral vector carrying the human IL-3 gene and cotransplanted subcutaneously as additional source of growth factor. Cotransplants of this cell line producing sustained in vivo levels of circulating human IL-3 for at least 12 weeks significantly accelerated the process of engraftment of huPBSC and spurred the spread of mature human cells to the murine spleen, liver, thymus, and peripheral blood. Cotransplants of allogeneic human bone marrow stromal cells derived from long-term cultures resulted in a comparable--though less prominent--support of engraftment.     

Transfer of Hexon‐ and Penton‐selected adenovirus‐specific T cells for refractory adenovirus infection after haploidentical stem cell transplantation

Adenovirus (HAdV) infections confer a high risk of morbidity and mortality for immunocompromised patients after stem cell transplantation (SCT). Treatment with standard antiviral drugs is of limited efficacy and associated with a high rate of adverse effects. HAdV‐specific T cells are crucial for sustained viral elimination and the efficacy of adoptive T‐cell therapy with donor‐derived HAdV‐specific T cells has been reported by several investigators. Here, we report our experience with the transfer of HAdV‐specific T cells specific for penton, which was recently identified as an immunodominant target of T cells, and hexon in a 14‐year‐old boy after T‐cell‐depleted haploidentical SCT for myelodysplastic syndrome (MDS). He developed severe HAdV‐associated enteritis complicated by acute graft‐versus‐host disease (GvHD). The patient received ten infusions of allogeneic HAdV‐specific T cells manufactured from the haploidentical stem cell donor using the CliniMacs Interferon‐γ (IFN‐γ) cytokine capture and immunomagnetic selection. Initially, T cells were generated against the immunodominant target hexon and in subsequent transfers dual antigen‐specific T cells against hexon and penton were applied. T‐cell transfers were scheduled individually tailored to current immunosuppressive treatment. Each transfer was followed by reduction of HAdV load in peripheral blood and clinical improvement. Importantly, T‐cell responses to both penton and hexon pools emerged in patient blood after repetitive transfers. Unfortunately, the patient experienced bacterial sepsis, and in this context, severe GvHD requiring intensive immunosuppression followed by secondary progression of HAdV infection. The patient succumbed to multiorgan failure 283 days after SCT. This case demonstrates the feasibility of HAdV‐specific T‐cell transfer even in the presence of immunosuppressive treatment. Targeting of multiple immunodominant viral proteins may prove valuable in patients with complicated HAdV infections.     

Ueber den Gasgehalt der Schwimmblase einiger Süsswasserfische Deutschlands

Ohne Zusammenfassung     

Magnetic resonance imaging of renal transplants: its value in the differentiation of acute rejection and cyclosporin A nephrotoxicity

The purpose of this study was to determine the value of magnetic resonance imaging (MRI) in the differentiation of acute rejection and cyclosporin A nephrotoxicity in renal transplant kidneys. Fifty-six magnetic resonance examinations in 46 patients were prospectively and independently evaluated by two radiologists. MRI was performed with a 0.5 T superconducting scanner (Gyroscan S5, Philips) applying both T1 and T2 weighted pulse sequences. Biopsies were performed in 22 cases and histology was reviewed. Fifteen normally functioning transplant kidneys and 41 kidneys with graft dysfunction due to cyclosporin A nephrotoxicity, acute rejection, chronic rejection or acute tubular necrosis were studied. Absence or reduction in cortico-medullary demarcation proved to be a sensitive, but non-specific indicator of parenchymal disease. In cases of cyclosporin A nephrotoxicity the allograft was diagnosed as being normal in 90%. The magnetic resonance appearance of acute rejection may be very similar to that of the combination of acute rejection and cyclosporin A nephrotoxicity, chronic rejection or acute tubular necrosis. However differentiation between acute rejection and cyclosporin A nephrotoxicity was possible according to the following statistical data: sensitivity 100%, specificity 75%, positive predictive value 86%, negative predictive value 100%, accuracy 90%.     

Assessment of Needle Guidance Devices for Their Potential to Reduce Fluoroscopy Time and Operator Hand Dose during C-Arm Cone-Beam Computed Tomography–guided Needle Interventions

PurposeTo assess whether the use of needle guidance devices can reduce fluoroscopy time and operator hand dose during cone-beam computed tomography–guided needle interventions.Materials and MethodsThe freehand technique was compared with techniques employing two distinct needle holders and a ceiling-mounted laser guidance technique. Laser guidance was used either alone or in combination with needle holders. Four interventional radiologists were instructed to reach predetermined targets in an abdominal phantom using these techniques. Each operator used all six techniques three times. Fluoroscopy time, procedure time, operator hand dose, and needle tip deviation were obtained for all simulated needle interventions. All data are presented as median (ranges).ResultsAll procedures were successfully completed within 2–4 minutes, resulting in a deviation from target of 0.8 mm (0–4.7). In freehand procedures, the fluoroscopy time to reach the target was 50 seconds (31–98 s). Laser guidance, used alone or in combination with needle holders, reduced fluoroscopy time to 31 seconds (14–68 s) (P<.02). The operator hand dose in freehand procedures was 275 μSv (20–603 μSv). Laser guidance alone or in combination with needle holders resulted in a reduction of the hand dose to<36 μSv (5–82 μSv) per procedure (P<.001). There were no statistically significant effects on hand dose levels or fluoroscopy time when the needle holders were employed alone.ConclusionsCompared with the freehand technique, all three tested needle guidance devices performed with equivalent efficiency in terms of accuracy and procedure time. Only the addition of laser guidance was found to reduce both fluoroscopy time and operator hand dose.