Peripheral Tolerance of CD8 T Lymphocytes

SummaryWhereas high-avidity recognition of peptide-MHC complexes by developing T cells in the thymus results in deletion and promotes self-tolerance, such recognition by mature T cells in the periphery results in activation and clonal expansion. This dichotomy represents the basis of a dilemma that has stumped immunologists for many years, how are self-specific T cells tolerized in the periphery? There appear to be two important criteria used to achieve this goal. The first is that in the absence of inflammatory pathogens, tolerance is promoted when T cells recognize antigen presented by quiescent dendritic cells (DCs) expressing low levels of costimulatory molecules. A second critical factor that defines “self” and drives tolerance through deletion, anergy, or suppression is the persistence of antigen

Conflicted scientists: the “shared pool” dilemma of scientific advisory committees

Science advisors play a critical role in government policy making, yet these advisors are often equally attractive to regulated industry. Despite efforts to manage conflicts of interest among science advisors, allegations of conflict frequently plague advisory committee deliberations or outcomes. This article examines what we term the “shared pool” dilemma using data collected from 92 members of 11 US Food and Drug Administration advisory committees. The results suggested science advisors were generally positive about their experiences on advisory committees and viewed the committee process as impartial. Written comments suggested that advisors linked the neutrality of the process to the success of the FDA’s conflict-of-interest procedures. Even so, the advisors acknowledged the challenges associated with recruiting disinterested and qualified scientists to serve on advisory committees, reflecting the shared pool dilemma. Many advisors seemed more troubled about advisors participating when they lacked expertise than when they had minor conflicts of interest

Uncoupling of Proliferative Potential and Gain of Effector Function by CD8+ T Cells Responding to Self-Antigens

Professional antigen-presenting cells (APCs) are capable of transporting self-antigens from peripheral tissues to secondary lymphoid organs where they are presented to potentially autoreactive CD8+ T cells. In the absence of an inflammatory response, this results in immune tolerance. The presence of activated, antigen-specific CD4+ T cells converts this tolerogenic encounter into an immunogenic one by promoting extensive proliferation of CD8+ T cells and their development into effectors. Surprisingly, activation of APCs with an agonistic antibody specific for CD40 could not substitute for CD4+ help in this task. Anti-CD40 induced recruitment of dendritic cells expressing high levels of B7 costimulatory molecules into the lymph nodes, which in turn, greatly enhanced activation and expansion of CD8+ T cells. However, these activated CD8+ cells did not demonstrate effector function. We conclude that proliferative potential and gain of effector function are separable events in the differentiation program of CD8+ T cells

Idd9.2 and Idd9.3 Protective Alleles Function in CD4+ T-Cells and Nonlymphoid Cells to Prevent Expansion of Pathogenic Islet-Specific CD8+ T-Cells

OBJECTIVE - Multiple type 1 diabetes susceptibility genes have now been identified in both humans and mice, yet mechanistic understanding of how they impact disease pathogenesis is still minimal. We have sought to dissect the cellular basis for how the highly protective mouse Idd9 region limits the expansion of autoreactive CD8 T-cells, a key cell type in destruction of the islets. RESEARCH DESIGN AND METHODS - We assess the endogenous CD8 T-cell repertoire for reactivity to the islet antigen glucose-6-phosphatase-related protein (IGRP). Through the use of adoptively transferred T-cells, bone marrow chimeras, and reconstituted severe combined immunodeficient mice, we identify the protective cell types involved. RESULTS - IGRP-specific CD8 T-cells are present at low frequency in the insulitic lesions of Idd9 mice and could not be recalled in the periphery by viral expansion. We show that Idd9 genes act extrinsically to the CD8 T-cell to prevent the massive expansion of pathogenic effectors near the time of disease onset that occurs in NOD mice. The subregions Idd9.2 and Idd9.3 mediated this effect. Interestingly, the Idd9.1 region, which provides significant protection from disease, did not prevent the expansion of autoreactive CD8 T-cells. Expression of Idd9 genes was required by both CD4 T-cells and a nonlymphoid cell to induce optimal tolerance. CONCLUSIONS - Idd9 protective alleles are associated with reduced expansion of IGRP-specific CD8 T-cells. Intrinsic expression of protective Idd9 alleles in CD4 T-cells and nonlymphoid cells is required to achieve an optimal level of tolerance. Protective alleles in the Idd9.2 congenic subregion are required for the maximal reduction of islet-specific CD8 T-cells

Middle Preclassic Period Maya Greenstone Triangulates : Forms, Contexts, and Geology of a Unique Mesoamerican Groundstone Artifact Type

Over the past twenty years our understanding of the Middle Preclassic (900–300 BCE) period has become much clearer through archaeological investigations at a number of sites located in the Upper Belize River Valley region of the eastern Maya Lowlands. While the picture of Middle Preclassic Maya life, including their material culture, has sharpened, there are aspects that remain uninvestigated. One artifact type, identified as greenstone triangulates, has been found at several Belize Valley sites and in a variety of contexts. Although a number of these multifaceted, polished groundstone items have been recovered, little research has focused on their distribution and function in the archaeological record. An evaluation of these items from primary contexts provides data for determining how they were used in daily social and/or ritual activities throughout the lowlands. Comparative data from other regions of Mesoamerica are also discussed. A detailed geological and petrographic pilot study of a sample of greenstone triangulates is provided, pointing conclusively to early, long-distance and complex exchange networks in exotic raw materials

Reducing Decisional Conflict and Enhancing Satisfaction with Information among Women Considering Breast Reconstruction following Mastectomy: Results from the BRECONDA Randomized Controlled Trial

Background: Deciding whether or not to have breast reconstruction following breast cancer diagnosis is a complex decision process. This randomized controlled trial assessed the impact of an online decision aid [Breast RECONstruction Decision Aid (BRECONDA)] on breast reconstruction decision-making. Methods: Women (n = 222) diagnosed with breast cancer or ductal carcinoma in situ, and eligible for reconstruction following mastectomy, completed an online baseline questionnaire. They were then assigned randomly to receive either standard online information about breast reconstruction (control) or standard information plus access to BRECONDA (intervention). Participants then completed questionnaires at 1 and 6 months after randomization. The primary outcome was participants' decisional conflict 1 month after exposure to the intervention. Secondary outcomes included decisional conflict at 6 months, satisfaction with information at 1 and 6 months, and 6-month decisional regret. Results: Linear mixed-model analyses revealed that 1-month decisional conflict was significantly lower in the intervention group (27.18) compared with the control group (35.5). This difference was also sustained at the 6-month follow-up. Intervention participants reported greater satisfaction with information at 1- and 6-month follow-up, and there was a nonsignificant trend for lower decisional regret in the intervention group at 6-month follow-up. Intervention participants' ratings for BRECONDA demonstrated high user acceptability and overall satisfaction. Conclusions: Women who accessed BRECONDA benefited by experiencing significantly less decisional conflict and being more satisfied with information regarding the reconstruction decisional process than women receiving standard care alone. These findings support the efficacy of BRECONDA in helping women to arrive at their breast reconstruction decision

Epidemiologic Risk Factors for In Situ and Invasive Breast Cancers Among Postmenopausal Women in the National Institutes of Health-AARP Diet and Health Study

Comparing risk factor associations between invasive breast cancers and possible precursors may further our understanding of factors related to initiation versus progression. Accordingly, among 190,325 postmenopausal participants in the National Institutes of Health-AARP Diet and Health Study (1995-2011), we compared the association between risk factors and incident ductal carcinoma in situ (DCIS; n = 1,453) with that of risk factors and invasive ductal carcinomas (n = 7,525); in addition, we compared the association between risk factors and lobular carcinoma in situ (LCIS; n = 186) with that of risk factors and invasive lobular carcinomas (n = 1,191). Hazard ratios and 95% confidence intervals were estimated from multivariable Cox proportional hazards regression models. We used case-only multivariable logistic regression to test for heterogeneity in associations. Younger age at menopause was associated with a higher risk of DCIS but lower risks of LCIS and invasive ductal carcinomas (P for heterogeneity < 0.01). Prior breast biopsy was more strongly associated with the risk of LCIS than the risk of DCIS (P for heterogeneity = 0.04). Increased risks associated with use of menopausal hormone therapy were stronger for LCIS than DCIS (P for heterogeneity = 0.03) and invasive lobular carcinomas (P for heterogeneity < 0.01). Associations were similar for race, age at menarche, age at first birth, family history, alcohol consumption, and smoking status, which suggests that most risk factor associations are similar for in situ and invasive cancers and may influence early stages of tumorigenesis. The differential associations observed for various factors may provide important clues for understanding the etiology of certain breast cancers