Transmission of Balamuthia mandrillaris by Organ Transplantation.

BACKGROUND: During 2009 and 2010, 2 clusters of organ transplant-transmitted Balamuthia mandrillaris, a free-living ameba, were detected by recognition of severe unexpected illness in multiple recipients from the same donor. METHODS: We investigated all recipients and the 2 donors through interview, medical record review, and testing of available specimens retrospectively. Surviving recipients were tested and treated prospectively. RESULTS: In the 2009 cluster of illness, 2 kidney recipients were infected and 1 died. The donor had Balamuthia encephalitis confirmed on autopsy. In the 2010 cluster, the liver and kidney-pancreas recipients developed Balamuthia encephalitis and died. The donor had a clinical syndrome consistent with Balamuthia infection and serologic evidence of infection. In both clusters, the 2 asymptomatic recipients were treated expectantly and survived; 1 asymptomatic recipient in each cluster had serologic evidence of exposure that decreased over time. Both donors had been presumptively diagnosed with other neurologic diseases prior to organ procurement. CONCLUSIONS: Balamuthia can be transmitted through organ transplantation with an observed incubation time of 17-24 days. Clinicians should be aware of Balamuthia as a cause of encephalitis with high rate of fatality, and should notify public health departments and evaluate transplant recipients from donors with signs of possible encephalitis to facilitate early diagnosis and targeted treatment. Organ procurement organizations and transplant centers should be aware of the potential for Balamuthia infection in donors with possible encephalitis and also assess donors carefully for signs of neurologic infection that may have been misdiagnosed as stroke or as noninfectious forms of encephalitis.

Lipid emulsion use precluding renal replacement therapy.

BACKGROUND: Intralipid emulsion (ILE) is a nutritional fatty acid supplementation that is emerging as a potential therapy for local anesthetic systemic toxicity and is also being considered as a therapy for other lipophilic medication intoxications. Isolated reports of pulmonary edema or severe lipemia exist as a complication of therapy. CASE REPORT: A 26-year-old hypertensive, male, kidney transplant recipient presented to an outside emergency department (ED) after an intentional overdose of his medications (ie, amlodipine, metoprolol, lisinopril). At presentation, he had hypotension and bradycardia that was unresponsive to treatment with intravenous saline, calcium, glucagon, and vasopressors. After failure of conventional therapy, an initial bolus of ILE (20%) was given with some improvement in his heart rate, and the dose was repeated. A continuous intravenous infusion of ILE therapy was started. The patient deteriorated, with development of both acute respiratory and renal failure. Continuous venovenous hemofiltration (CVVHF) was attempted to remove volume and correct metabolic abnormalities. Lipemic blood was immediately observed in the CVVHF filter. After 15 min, the transmembrane pressures of the filter began to rise in the absence of observed clotting of the blood and the filter then became completely obstructed. An attempt was made to remove the lipid by plasmapheresis to restart CVVHF, but the patient continued to deteriorate despite maximal vasopressor support. The patient's family decided to withdraw care and the patient expired. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians treat patients with toxic ingestions on a regular basis. Being aware of possible complications of experimental antidote therapy, like ILE, can improve the treatment approach and outcomes for these patients.

BK virus in the kidney transplant patient.

BK virus, a member of the polyomavirus family, is a well-recognized cause of irreversible graft failure after kidney transplantation. Awareness of the relationship between BK infection and immunosuppression along with better understanding of its pathogenesis has contributed to increasing rates of its diagnosis. Current therapies are aimed at early diagnosis, limiting inflammation caused by the virus and elimination of the virus through different strategies. The epidemiology, pathogenesis and the different modalities of therapy available are discussed in this review along with the approach to retransplantation in the setting of graft failure from BK infection.

Systems biology of vaccination for seasonal influenza in humans.

Here we have used a systems biology approach to study innate and adaptive responses to vaccination against influenza in humans during three consecutive influenza seasons. We studied healthy adults vaccinated with trivalent inactivated influenza vaccine (TIV) or live attenuated influenza vaccine (LAIV). TIV induced higher antibody titers and more plasmablasts than LAIV did. In subjects vaccinated with TIV, early molecular signatures correlated with and could be used to accurately predict later antibody titers in two independent trials. Notably, expression of the kinase CaMKIV at day 3 was inversely correlated with later antibody titers. Vaccination of CaMKIV-deficient mice with TIV induced enhanced antigen-specific antibody titers, which demonstrated an unappreciated role for CaMKIV in the regulation of antibody responses. Thus, systems approaches can be used to predict immunogenicity and provide new mechanistic insights about vaccines.

T-cell receptor-stimulated calcineurin activity is inhibited in isolated T cells from transplant patients.

The addition of calcineurin inhibitors, including cyclosporine A (CsA) and FK-506 (tacrolimus), to transplant protocols has markedly reduced acute allograft rejection and prolonged patient survival. Although monitoring of serum drug levels has been shown to be a poor indicator of efficacy, there is little data on calcineurin enzymatic activity in humans. Therefore, we measured calcineurin in isolated CD3(+)/4(+) T cells from 81 non-transplant controls and 39 renal allograft patients by using a (32)PO(4)-labeled calcineurin-specific substrate. A gender difference was observed in the control cohort, with activity in males significantly higher than that in females (1073 +/- 134 versus 758 +/- 75 fmol/microg/min, respectively). Activity of both groups was comparably inhibited by 5 ng/ml tacrolimus (27 +/- 4 versus 30 +/- 4%). Calcineurin is a downstream target of the T-cell receptor (TCR). Therefore, activity was measured in isolated T cells after incubation with anti-CD3/CD28 antibodies to stimulate the TCR. Calcineurin activity increased significantly from 1214 +/- 111 to 1652 +/- 138 fmol/microg/min; addition of either tacrolimus or CsA (500 ng/ml) blocked CD3/CD28 stimulation. Despite therapeutic levels of tacrolimus and CsA (mean 11.4 and 172 ng/ml), basal calcineurin activity was significantly higher among renal transplant recipients than controls (1776 +/- 175 versus 914 +/- 78 fmol/microg/min). In contrast, anti-CD3/CD28 antibodies failed to stimulate calcineurin activity in transplant subjects. Finally, we found that basal and stimulated calcineurin activities are inversely related. Consistent with this finding, basal activity in resting T cells rose over time after transplant but stimulation fell (r(2) = 0.785, p < 0.05). These data suggest that examination of TCR-stimulated calcineurin activity after renal transplantation may be useful for monitoring immunosuppression of individual patients.

Immune responsiveness and protective immunity after transplantation.

The growing success of solid organ transplantation poses unique challenges for the implementation of effective immunization strategies. Although live attenuated vaccines have proven benefits for the general population, immunosuppressed patients are at risk for unique complications such as infection from the vaccine because of lack of both clearance and containment of a live attenuated virus. Moreover, while vaccination strategies using killed organisms or purified peptides are believed to be safe for immunosuppressed patients, they may have reduced efficacy in this population. The current lack of knowledge of the basic safety and efficacy of vaccination strategies in the immunosuppressed has limited the development of guidelines regarding vaccination in this population. Recent fears of influenza pandemics and potential attacks by weaponized pathogens such as smallpox heighten the need for increased knowledge. Herein, we review the current understanding of the effects of immunosuppressants on the immune system and the ability of the suppressed immune system to respond to vaccination. This review highlights the need for systematic, longitudinal studies in both humans and nonhuman primates to understand better the defects in innate and adaptive immunity in transplant recipients, thereby aiding the development of strategies to vaccinate these individuals.

Heterologous immunity provides a potent barrier to transplantation tolerance.

Many strategies have been proposed to induce tolerance to transplanted tissue in rodents; however, few if any have shown equal efficacy when tested in nonhuman primate transplant models. We hypothesized that a critical distinction between specific pathogen-free mice and nonhuman primates or human patients is their acquired immune history. Here, we show that a heterologous immune response--specifically, virally induced alloreactive memory--is a potent barrier to tolerance induction. A critical threshold of memory T cells is needed to promote rejection, and CD8(+) "central" memory T cells are primarily responsible. Finally, treatment with deoxyspergualin, an inhibitor of NF-kappa B translocation, together with costimulation blockade, synergistically impairs memory T cell activation and promotes antigen-specific tolerance of memory. These data offer a potential explanation for the difficulty encountered when inducing tolerance in nonhuman primates and human patients and provide insight into the signaling pathways essential for memory T cell activation and function.

Cutting edge: perforin down-regulates CD4 and CD8 T cell-mediated immune responses to a transplanted organ.

Perforin mediates target cell apoptosis by CTLs and NK cells. Although perforin expression correlates strongly with acute allograft rejection, perforin-deficient mice reject allografts with the same kinetics as wild-type recipients. In this study, we tested the hypothesis that while perforin is dispensable for acute rejection, it is essential for down-regulating the alloimmune response by inducing the apoptosis of host immune cells. Using a skin transplantation model, we found that perforin-deficient mice are resistant to the induction of allograft acceptance by agents that block T cell costimulation. Failure to induce allograft acceptance in these mice was observed irrespective of whether the alloimmune response was CD4 or CD8 T cell-mediated and could be attributed to defective apoptosis of activated CD4 and CD8 T cells. In contrast, perforin did not influence T cell proliferation. Therefore, perforin is an essential immunoregulatory molecule that may be required for the induction of transplantation tolerance.