T lymphocyte receptor CTLA-4 binds costimulatory molecules CD80 (B7-1) and CD86 (B7-2) with high avidity and negatively regulates T cell activation. CTLA-4 functions at the cell surface, yet is ...primarily localized in intracellular vesicles. Here, we demonstrate cycling of CTLA-4 between intracellular stores and the cell surface. Intracellular vesicles containing CTLA-4 overlapped with endocytic compartment(s) and with perforin-containing secretory granules. Cell surface expression of CTLA-4 was rapidly increased by raising intracellular calcium levels. During T cell activation, intracellular and cell surface CTLA-4 became focused towards sites of TCR activation. Cycling and directional control of CTLA-4 expression may regulate its functional interaction with APCs bearing peptide–MHC complexes of appropriate specificity and avidity.
Family-centered care (FCC) is defined as an approach to care coordination founded in collaborative partnerships between healthcare providers, patients and their family caregivers. Amid the enthusiasm ...for FCC in the pediatric setting, opportunities have been identified to operationalize the engagement of pediatric, adolescent and young adult patients and their caregivers into decision making that translates not only to their healthcare, but also to the context in which care is provided, as well as the research informing their care. At a National Cancer Institute-designated comprehensive cancer center, the Children’s Cancer Hospital was instrumental in designing and implementing patient and family engagement councils to inform institutional policies, guidelines, environment of care and research. The councils include: he Family Advisory Council, the Supportive Care Council, the Young Adult Advisory Council, and the Patient Advisory Council for Teens (imPACT). The development and outcomes of these councils is presented as an exemplar for patient and family engagement that translates to tangible healthcare delivery initiatives.
In vitro, when the B7 molecule on the surface of antigen-presenting cells binds to the T cell surface molecules CD28 and CTLA-4, a costimulatory signal for T cell activation is generated. CTLA4Ig is ...a soluble form of the extracellular domain of CTLA-4 and binds B7 with high avidity. CTLA4Ig treatment in vivo suppressed T cell-dependent antibody responses to sheep erythrocytes or keyhole limpet hemocyanin. Large doses of CTLA4Ig suppressed responses to a second immunization. Thus, costimulation by B7 is important for humoral immune responses in vivo, and interference with costimulation may be useful for treatment of antibody-mediated autoimmune disease.
The B7-related molecules CD80 and CD86 are expressed on antigen-presenting cells, bind the homologous T cell receptors CD28 and CTLA-4, and trigger costimulatory signals important for optimal T cell ...activation. All four molecules are immunoglobulin superfamily members, each comprising an extracellular Ig variable-like (IgV) domain, with CD80 and CD86 containing an additional Ig constant-like (IgC) domain. Despite limited sequence identity, CD80 and CD86 share similar overall receptor binding properties and effector functions. We have identified, by site-directed mutagenesis of soluble forms of CD80 and CD86, residues in both the IgV and IgC domains that are important for CTLA4Ig and CD28Ig binding. Mutagenesis in the IgV domain of CD80 identified 11 amino acids that support receptor binding. Many of these residues are conserved in the B7 family, are hydrophobic, and approximately map to the GFCC′C″β-sheet face of an IgV fold. Mutagenesis of corresponding residues in CD86 established that some, but not all, of these residues also played a role in CD86 receptor binding. In general, mutations had a similar effect on CTLA4Ig and CD28Ig binding, thereby indicating that both receptors bind to overlapping sites on CD80 and CD86. Further, mutagenesis of several conserved residues in the ABED β-sheet face of the IgC domain of CD80 completely ablated receptor binding. Point mutagenesis had a more pronounced effect than complete truncation of the IgC domain. Thus, full CTLA4Ig and CD28Ig binding to B7 molecules is dependent upon residues in the GFC′C″ face of the IgV domain and the ABED face of the IgC domain.
Current success in organ transplantation is dependent upon the use of calcineurin‐inhibitor‐based immunosuppressive regimens. Unfortunately, current immunotherapy targets molecules with ubiquitous ...expression resulting in devastating non‐immune side effects. T‐cell costimulation has been identified as a new potential immunosuppressive target. The best characterized pathway includes CD28, its homologue CTLA4 and their ligands CD80 and CD86. While an immunoglobulin fusion protein construct of CTLA4 suppressed rejection in rodents, it lacked efficacy in primate transplant models. In an attempt to increase the biologic potency of the parent molecule a novel, modified version of CTLA4‐Ig, LEA29Y (belatacept), was constructed. Two amino acid substitutions (L104E and A29Y) gave rise to slower dissociation rates for both CD86 and CD80. The increased avidity resulted in a 10‐fold increase in potency in vitro and significant prolongation of renal allograft survival in a pre‐clinical primate model. The use of immunoselective biologics may provide effective maintenance immunosuppression while avoiding the collateral toxicities associated with conventional immunsuppressants.
T lymphocyte receptors CD28 and CTLA-4 bind costimulatory molecules CD80 (B7-1) and CD86 (B7-2) on antigen-presenting cells and regulate T cell activation. While distinct functional roles have been ...ascribed to each of these molecules, little is known about how they interact. To better characterize these interactions, we have used surface plasmon resonance to perform equilibrium and kinetic binding analyses of extracellular fragments of CD28/CTLA-4/CD80/CD86. We show that CTLA-4 and CD28 binding are both characterized by rapid kinetic on-rates and rapid dissociation rates. Native disulfide-linked homodimers of CD28 and CTLA-4 bound with two kinetically distinct binding sites, one of high avidity and slow dissociation and one of low avidity and more rapid dissociation. Monomeric CTLA-4 bound only with low affinity and rapid dissociation. Therefore, covalent dimerization of CTLA-4 is required for its high avidity binding. Oligomerization of CD80/CD86 is also required for high avidity CTLA-4 binding since CTLA-4 bound with low avidity to monomeric CD86. This contrasts with the ability of CD80/CD86 on antigen-presenting cells to bind CTLA4Ig with high avidity and predicts their organization as oligomers or clusters that permit multivalent binding. Thus, covalent receptor dimerization and ligand oligomerization are two key features of the CD28/CTLA-4/CD80/CD86 receptor system that control ligand binding and may regulate signal transduction by controlling the duration of receptor occupancy.
Deciding on the right mix of portfolio projects is crucial for the organization since poor decisions in its selection affect its value, resulting in a misallocation of resources and missed market ...opportunities. Despite the criticality of choosing an optimal project mix, portfolio decisions are often made in an equivocal environment where data is limited, resources are constrained, and projects are interdependent. These factors create considerable decision-making challenges and are the impetus behind this study’s orientation toward decision styles and the match to its context. Dual-process theory (DPT) references two styles: rational and intuitive. Quantitative and analytical project selection techniques capitalize on a rational decision style. However, the tools are complex, assume the availability of information, and often do not account for project interdependencies. The parallel-competitive variant of DPT asserts that intuition is well-suited for decision-making in such environments. Yet, an intuitive decision style requires experience and can create biased outcomes. Extant literature revealed that combining both styles provides good results since it can counter the adverse effects of each type while exploiting its benefits. These findings led to the following question: To what extent does the decision style of project portfolio decision-makers predict project portfolio success? A non-experimental correlational study (N = 105) that relied upon senior management and C-Suite portfolio decision-makers from US companies was designed to answer the following: 1. To what extent does the rational decision style of project portfolio decision-makers at companies with 500 or more employees predict project portfolio success? 2. To what extent does the intuitive decision style of project portfolio decision-makers at companies with 500 or more employees predict project portfolio success? 3. To what extent do the rational and intuitive decision styles combine to predict project portfolio success for decision-makers at companies with 500 or more employees? The dependent variable of project portfolio success was regressed on three predictors, rational decision style, intuitive decision style, and the product of the rational and intuitive style (i.e., a combined style), using robust, weighted least squares regression. The main model was positive and highly significant (robust F3, 101 = 74.69, p < .001). Simple slopes analysis revealed that the intuitive style strengthened the rational style, creating a positive interaction effect. The findings have broad implications. First, project portfolio decision-makers utilize intuition, with successful portfolios a predicted outcome. Such beneficial effects align with the parallel-competitive theory that places intuition on par with the analytical mind and holds theoretical significance. Thus, portfolio managers should feel free to apply intuitive judgment in addition to quantitative analytical techniques to portfolio decisions. Doing so can provide the decision-maker with the synergistic benefits of both methods, resulting in superior decisions than would be possible with either style alone.
Abstract A total of 104 patients, aged 18 to 70 years, with a diagnosis of chronic idiopathic myelofibrosis (CIMF), polycythemia vera (PV), or essential thrombocythemia (ET) with marrow fibrosis were ...transplanted from allogeneic (56 related and 45 unrelated) or syngeneic (n = 3) donors. Busulfan (BU) or total body irradiation (TBI)-based myeloablative conditioning regimens were used in 95 patients, and a nonmyeloablative regimen of fludarabine plus TBI was used in 9 patients. The source of stem cells was bone marrow in 43 patients and peripheral blood in 61 patients. A total of 63 patients were alive at a follow-up of 1.3–15.2 years (median, 5.3 years), for an estimated 7-year actuarial survival rate of 61%. Eleven patients had recurrent/persistent disease, of whom 8 died. Nonrelapse mortality was 34% at 5 years. Patients conditioned with targeted BU (plasma levels 800–900 ng/mL) plus cyclophosphamide (tBUCY) had a higher probability of survival (68%) than other patients. Dupriez score, platelet count, patient age, and comorbidity score were statistically significantly associated with mortality in univariate models. In a multivariable regression model, use of tBUCY ( P = .03), high platelet count at transplantation ( P = .01 for PV/ET; P = .39 for other diagnoses), younger patient age ( P = .04), and decreased comorbidity score ( P = .03) remained statistically significant for improved survival. Our findings show that hematopoietic cell transplantation offers potentially curative treatment for patients with ICMF, PV, or ET.
B7-0 or B7-2 (CD86) is a T cell costimulatory molecule that binds the same receptors (CD28 and CTLA-4) as B7-1 (CD80), but shares with it only ∼25% sequence identity and is expressed earlier during ...an immune response. Here we show that human CD86 maintains similar (within ∼2- to 3-fold) overall receptor binding and T cell costimulatory properties as CD80. However, CD80 and CD86 did not bind equivalently to CTLA-4: CD80 bound Y100A, a form of CTLA4Ig with a mutation in the CDR3-like region, >200-fold better than did CD86; inhibition of CD80-mediated cellular responses required ∼100-fold lower CTLA4Ig concentrations; and CD80-CTLA4Ig complexes dissociated 5- to 8-fold more slowly. Thus, CD80 and CD86 utilize different binding determinants and have different kinetics of binding to CD28 and CTLA-4.
Abstract Marrow fibrosis is considered a poor prognostic factor in patients with myelodysplastic syndrome (MDS). The affect of fibrosis on outcomes after hematopoietic cell transplantation (HCT) in ...patients with MDS has not been examined. We performed a retrospective analysis in 471 patients with MDS or acute myeloid leukemia with multilineage dysplasia arising from MDS, 113 with and 358 without marrow fibrosis, who received myeloablative allogeneic HCT. Post-HCT follow-up was 0.3–10 years (median, 3.6 years) for patients with, and 0.6–12 years (median, 5 years) for patients without fibrosis. Engraftment was significantly delayed in patients with fibrosis (hazard ratio HR = 0.4; P < .001). Overall, there were no significant differences in overall survival (OS), relapse-free survival (RFS), and nonrelapse mortality (NRM) between patients with and without fibrosis. However, among patients with advanced disease (int-2 or high-risk disease by the International Prognostic Scoring System), OS ( P = .03), RFS ( P = .04), and NRM ( P = .04) were inferior when marrow fibrosis was present. Given that marrow fibrosis is a poor prognostic factor for patients with MDS, and that it does not appear to affect outcome of transplantation in patients with earlier-stage disease but has a negative impact on outcome for patients with advanced disease, patients with earlier-stage MDS and marrow fibrosis might be considered for HCT earlier than their disease stage would normally dictate.
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