Of the multiple mechanisms leading to type 1 diabetes, T cell receptor revision may play a prominent role (is type 1 diabetes more than a single disease?).

A single determinant factor for autoimmunity does not exist; disease development probably involves contributions from genetics, the environment and immune dysfunction. Type 1 diabetes is no exception. Genomewide-associated studies (GWAS) analysis in T1D has proved disappointing in revealing contributors to disease prediction; the only reliable marker has been human leucocyte antigen (HLA). Specific HLAs include DR3/DR4/DQ2/DQ8, for example. Because HLA molecules present antigen to T cells, it is reasonable that certain HLA molecules have a higher affinity to present self-antigen. Recent studies have shown that additional polymorphisms in HLA that are restricted to autoimmune conditions are further contributory. A caveat is that not all individuals with the appropriate 'pro-autoimmune' HLA develop an autoimmune disease. Another crucial component is autoaggressive T cells. Finding a biomarker to discriminate autoaggressive T cells has been elusive. However, a subset of CD4 helper cells that express the CD40 receptor have been described as becoming pathogenic. An interesting function of CD40 on T cells is to induce the recombination-activating gene (RAG)1/RAG2 T cell receptor recombination machinery. This observation is contrary to immunology paradigms that changes in TCR molecules cannot take place outside the thymic microenvironment. Alteration in TCR, called TCR revision, not only occurs, but may help to account for the development of autoaggressive T cells. Another interesting facet is that type 1 diabetes (T1D) may be more than a single disease; that is, multiple cellular components contribute uniquely, but result ultimately in the same clinical outcome, T1D. This review considers the process of T cell maturation and how that could favor auto-aggressive T cell development in T1D. The potential contribution of TCR revision to autoimmunity is also considered.

Resolving the bulk ion region of millimeter-wave collective Thomson scattering spectra at ASDEX Upgrade.

Collective Thomson scattering (CTS) measurements provide information about the composition and velocity distribution of confined ion populations in fusion plasmas. The bulk ion part of the CTS spectrum is dominated by scattering off fluctuations driven by the motion of thermalized ion populations. It thus contains information about the ion temperature, rotation velocity, and plasma composition. To resolve the bulk ion region and access this information, we installed a fast acquisition system capable of sampling rates up to 12.5 GS/s in the CTS system at ASDEX Upgrade. CTS spectra with frequency resolution in the range of 1 MHz are then obtained through direct digitization and Fourier analysis of the CTS signal. We here describe the design, calibration, and operation of the fast receiver system and give examples of measured bulk ion CTS spectra showing the effects of changing ion temperature, rotation velocity, and plasma composition.

Increased expression of CD40 on thymocytes and peripheral T cells in autoimmunity: a mechanism for acquiring changes in the peripheral T cell receptor repertoire.

CD40, a cell surface molecule found on B lymphocytes and other antigen presenting cells, can, when engaged by CD40 ligand (CD40L), induce gene rearrangements and isotype switching. We report here that CD40 is also expressed on thymocytes and on up to 50% of peripheral T cells from autoimmune prone strains of mice. In normal animals, CD40 is present on a small population of T cells and thymocytes. CD40 is expressed on most T cell hybridomas. We demonstrate that CD40 engagement on peripheral T cells, T cell hybridomas and thymocytes results in altered TCRValpha expression. That induced expression of different Valpha's results from the activity of the recombinase gene is implied by the observation that CD40 does not induce TCR changes in RAG knock-out mice. Total cell numbers remained unchanged between anti-CD40 treated and untreated populations of thymocytes or T cells indicating that treatment does not induce cell proliferation or cell death. The data presented here suggest a mechanism by which self reactive T cells accumulate peripherally and independently of selective processes of the thymus.

gamma delta+ T cells regulate major histocompatibility complex class II(IA and IE)-dependent susceptibility to coxsackievirus B3-induced autoimmune myocarditis.

Coxsackievirus B3 (CVB3) infection induces myocardial inflammation and myocyte necrosis in some, but not all, strains of mice. C57BL/6 mice, which inherently lack major histocompatibility complex (MHC) class II IE antigen, develop minimal cardiac lesions despite high levels of virus in the heart. The present experiments evaluate the relative roles of class II IA and IE expression on myocarditis susceptibility in four transgenic C57BL/6 mouse strains differing in MHC class II antigen expression. Animals lacking MHC class II IE antigen (C57BL/6 [IA+ IE-] and ABo [IA- IE-]) developed minimal cardiac lesions subsequent to infection despite high concentrations of virus in the heart. In contrast, strains expressing IE (ABo Ealpha [IA- IE+] and Bl.Tg.Ealpha [IA+ IE+]) had substantial cardiac injury. Myocarditis susceptibility correlated to a Th1 (gamma interferon-positive) cell response in the spleen, while disease resistance correlated to a preferential Th2 (interleukin-4-positive) phenotype. Vgamma/Vdelta analysis indicates that distinct subpopulations of gamma delta+ T cells are activated after CVB3 infection of C57BL/6 and Bl.Tg.Ealpha mice. Depletion of gamma delta+ T cells abrogated myocarditis susceptibility in IE+ animals and resulted in a Th1-->Th2 phenotype shift. These studies indicate that the MHC class II antigen haplotype controls myocarditis susceptibility, that this control is most likely mediated through the type of gamma delta T cells activated during CVB3 infection, and finally that different subpopulations of gamma delta+ T cells may either promote or inhibit Th1 cell responses.

IL-4 and IL-10 modulation of CD40-mediated signaling of monocyte IL-1beta synthesis and rescue from apoptosis.

Previous studies have demonstrated that the interaction of CD40 on monocytes with CD40 ligand, present on activated CD4+ T cells, induces monocyte inflammatory cytokine synthesis and rescues monocytes from apoptosis. These findings suggest a role for CD40 signaling of monocyte activation in the maintenance and/or exacerbation of nonseptic (e.g., autoimmune) inflammatory responses. In the present study the effects of the modulatory cytokines IL-4 and IL-10 on CD40-mediated signaling of monocyte IL-1beta synthesis and rescue from apoptosis were examined. Both IL-4 and IL-10 decreased CD40-dependent IL-1beta synthesis in a dose-dependent manner individually and synergized in this effect when used concurrently, with minimal effect on CD40 surface expression. CD40 signaling of IL-1beta synthesis was shown to be dependent on the induction of protein tyrosine kinase (PTK) activity, and both IL-4 and IL-10 diminished CD40-mediated tyrosine phosphorylation of monocyte cellular proteins. However, IL-4, but not IL-10, blocked CD40-mediated rescue from apoptosis, an event that we have demonstrated previously to be dependent on PTK activity as well. Together these results suggest that in monocytes 1) both IL-4 and IL-10 target CD40-induced PTK activity in the down-regulation of IL-1beta synthesis; and 2) IL-4 and IL-10 have divergent effects on the CD40 signaling pathway, in that these cytokines are synergistic with respect to their abilities to inhibit CD40-mediated IL-1beta synthesis and differ in their abilities to block CD40-mediated rescue from apoptosis.

Rescue of thymocytes from glucocorticoid-induced cell death mediated by CD28/CTLA-4 costimulatory interactions with B7-1/B7-2.

During the differentiation of thymocytes to mature T cells the processes of positive and negative selection result in signals that either protect thymocytes from cell death, or delete, through apoptosis, thymocytes with self-reactive T cell receptors (TCR). Glucocorticoids have been shown to induce thymocyte apoptosis and are produced within the thymic microenvironment. Furthermore, steroid-induced apoptosis of thymocytes has been suggested as a potential mechanism for removal of nonselected thymocytes. In this report, we demonstrate that thymocytes can be rescued from glucocorticoid-induced apoptosis by incubation with cells that express high levels of B7-1 or B7-2. In addition, the ability to be rescued by B7-1 and/or B7-2 can precede expression of the TCR. We demonstrate that CD3(+)-depleted or CD3+/ TCR-beta(+)-doubly depleted thymocytes can be rescued from glucocorticoid-induced apoptosis through the interaction of CD28 or CTLA-4 on thymocytes with cells bearing high levels of B7-1 or B7-2. Furthermore, these transfected cells are major histocompatibility complex (MHC) class II negative and, while they may express MHC class I, there is no preferential rescue of CD8+ thymocytes in the presence of glucocorticoids. Together, these data suggest that the rescue of thymocytes from glucocorticoids can be independent of the TCR. We also demonstrate that, in addition to CD28, CTLA-4 is expressed on thymocytes, suggesting that rescue from glucocorticoid-induced cell death can be mediated by both CD28 and CTLA-4. A CTLA-4Ig fusion protein which binds to both B7-1 and B7-2 was shown to completely block the rescue of thymocytes from glucocorticoid-induced cell death. Therefore, we conclude that interactions between B7-1/B7-2 and CD28/CTLA-4 are sufficient and necessary for rescue of thymocytes from glucocorticoid-induced cell death.

Role of the CD40-CD40 ligand interaction in CD4+ T cell contact-dependent activation of monocyte interleukin-1 synthesis.

Most studies of the induction of cytokine synthesis in monocytes have employed an exogenous triggering agent such as lipopolysaccharide. However, in nonseptic inflammatory responses (e.g. rheumatoid arthritis) monocyte activation occurs as a result of T cell-generated signals. In previous reports, we and others have demonstrated that contact-dependent T cell-generated signals are capable of contributing to macrophage activation. We have shown that plasma membranes from anti-CD3 activated purified peripheral CD4+ T cells (TmA) but not from resting CD4+ cells (TmR) induce monocytes to synthesize interleukin (IL)-1 in the absence of co-stimulatory cytokines. Studies to determine the expression kinetics of the molecule(s) unique to activated CD4+ T cells which interact with monocytes to induce IL-1 revealed that optimal expression occurred at 6 h post activation. This matched the previously reported kinetics of expression of CD40 ligand (CD40L) on activated peripheral T cells, implicating the CD40-CD40L interaction as a candidate for the initiator of the IL-1 signaling event. The ability of TmA to induce IL-1 synthesis in resting monocytes could be markedly reduced by addition of a monoclonal anti-CD40L antibody, 5c8. In addition, a monoclonal anti-CD40 IgM (BL-C4) proved dramatic in its ability to induce resting monocytes to synthesize IL-1. In summary, these results demonstrate that the CD40-CD40L interaction provides a critical component of CD4+ T cell contact-dependent activation of monocyte IL-1 synthesis.

Abnormal protein translocation as the elusive cause of cystic fibrosis: an hypothesis.

Despite the recent rapid advances in isolation of the abnormal gene responsible for cystic fibrosis, there remains the need to explain the mechanism by which a single gene mutation causes the widespread clinical effects seen in this disease. Careful review of the otherwise unexplained abnormalities of cystic fibrosis from the perspective of cell biology reveals the following common features: (1) all these abnormalities involve proteins which are either (A) inserted into cell membranes in the RER and arrested after partial translocation or (B) inserted into RER membranes and fully translocated to be compartmentalized away from the cytosol in secretory vacuoles, lysosomes or peroxisomes; (2) all the involved proteins have minor abnormalities in their physicochemical properties or activity functions; (3) none of the involved proteins are missing or totally deficient in function; (4) final compartmentalization of the involved proteins is unaffected. These observations have directed our attention to the process by which most proteins are inserted into and translocated across lipid bilayer membranes, namely the signal peptide mechanism. This mechanism, not previously examined in cystic fibrosis, is reviewed in detail. Of the major proteins controlling signal peptide translocation, deficiencies in the function of signal peptidase activity appear most capable of causing the effects seen in cystic fibrosis.

Identifying the right nurse manager. An objective selection process.

Over the past 3 years, 15 successful nurse managers have been chosen using an objective selection process developed by the authors. A process to help the nurse executive answer the question, Am I choosing the right person for this job? is described. Through the use of an applicant assessment process, a candidate's leadership ability is revealed, and subjectivity in selection is considerably reduced.

A review of one hundred and fifty thyroidectomies following prior irradiation to the head, neck and upper part of the chest.

The records of 150 patients who had operations on the thyroid following prior irradiation to the head, neck and chest regions were analyzed. The over-all incidence of carcinoma of the thyroid in these patients was 32 per cent; however, 8.6 per cent of these were occult microscopic tumors. The technetium scan was found to be a reliable method of identifying nodules of the thyroid, while physical examination proved to be a less accurate method of nodule detection. The multifocal nature of the disease was confirmed in this series in which a 68 per cent incidence of residual carcinoma was detected in patients in whom reoperation was required.