Defective B cell development and function in Btk-deficient mice

Mutations in the Bruton's tyrosine kinase (Btk) gene have been linked to severe early B cell developmental blocks in human X-linked agammaglobulinemia (XLA), and to milder B cell activation deficiencies in murine X-linked immune deficiency (Xid). To elucidate unequivocally potential Btk functions in mice, we generated mutations in embryonic stem cells, which eliminated the ability to encode Btk pleckstrin homology or kinase domains, and assayed their effects by RAG2-deficient blastocyst complementation or introduction into the germline. Both mutations block expression of Btk protein and lead to reduced numbers of mature conventional B cells, severe B1 cell deficiency, serum IgM and IgG3 deficiency, and defective responses in vitro to various B cell activators and in vivo to immunization with thymus-independent type II antigens. These results prove that lack of Btk function results in an Xid phenotype and further suggest a differential requirement for Btk during the early stages of murine versus human B lymphocyte development.

Elimination from peripheral lymphoid tissues of self-reactive B lymphocytes recognizing membrane-bound antigens

The long-standing hypothesis that tolerance to self antigens is mediated by either elimination or functional inactivation (anergy) or self-reactive lymphocytes is now accepted, but little is known about the factors responsible for initiating one process rather than the other. In the B-cell lineage, tolerant self-reactive cells persist in the peripheral lymphoid organs of transgenic mice expressing lysozyme and anti-lysozyme immunoglobulin genes, but are eliminated in similar transgenic mice expressing anti-major histocompatibility complex immunoglobulin genes. By modifying the structure of the lysozyme transgene and the isotype of the anti-lysozyme immunoglobulin genes, we demonstrate here that induction of anergy or deletion is not due to differences in antibody affinity or isotype, but to recognition of monomeric or oligomeric soluble antigen versus highly multivalent membrane-bound antigen. Our findings indicate that the degree of receptor crosslinking can have qualitatively distinct signalling consequences for lymphocyte development.

Origin of murine B cell lineages

Until recently, the hematopoietic stem cells (HSC) that appear early in ontogeny were thought to constitute a homogeneous, self-replenishing population whose developmental potential remains constant throughout the life of the animal. Studies reviewed here, however, demonstrated clear differences in the developmental potential of fetal and adult progenitor populations (including FACS-sorted HSC). These studies, which chart the ability of various progenitor sources to reconstitute functionally distinct B cell populations, define three B cell lineages: B-1a cells (CD5 B cells), derived from progenitors that are present in fetal omentum and fetal liver but are largely absent from adult bone marrow; B-1b cells ("sister" population), derived from progenitors that are present in fetal omentum, fetal liver, and also in adult bone marrow; and conventional B cells, whose progenitors are missing from fetal omentum but are found in fetal liver and adult bone marrow. B-1a and B-1b cells share many properties, including self-replenishment and feedback regulation of development. These B cell studies, in conjunction with evidence for a similar developmental switch for T cells and erythrocytes, suggest that evolution has created a "layered" immune system in which successive progenitors (HSC) reach predominance during development and give rise to differentiated cells (B, T, etc) responsible for progressively more complex immune functions.

Nonoperative salvage of computed tomography-diagnosed splenic injuries: utilization of angiography for triage and embolization for hemostasis

OBJECTIVES

The aims of this study were to determine if angiographic findings can be used to predict successful nonoperative therapy of splenic injury and to determine if coil embolization of the proximal splenic artery provides effective hemostasis.

METHODS

Splenic injuries detected by diagnostic imaging between 1981 and 1993 at a level I trauma center were prospectively collected and retrospectively reviewed after management by protocol that used diagnostic peritoneal lavage, computed tomography (CT), angiography, transcatheter embolization, and laparotomy. Computed tomography was performed initially or after positive diagnostic peritoneal lavage. Angiography was performed urgently in stabilized patients with CT-diagnosed splenic injuries. Patients without angiographic extravasation were treated by bed rest alone; those with angiographic extravasation underwent coil embolization of the proximal splenic artery followed by bed rest.

RESULTS

Patients (172) with blunt splenic injury are the subject of this study. Twenty-two patients were initially managed operatively because of associated injuries or disease (11 patients) or because the surgeon was unwilling to attempt nonoperative therapy (11 patients) and underwent splenectomy (17 patients) or splenorrhaphy (5 patients). One hundred fifty of 172 consecutive patients (87%) with CT-diagnosed splenic injury were stable enough to be considered for nonoperative management. Eighty-seven of the 90 patients managed by bed rest alone, and 56 of 60 patients treated by splenic artery occlusion and bed rest had a successful outcome. Overall splenic salvage was 88%. It was 97% among those managed nonoperatively, including 61 grade III and grade IV splenic injuries. Sixty percent of patients received no blood transfusions. Three of 150 patients treated nonoperatively underwent delayed splenectomy for infarction (one patient) or splenic infection (two patients).

CONCLUSIONS

(1) Hemodynamically stable patients with splenic injuries of all grades and no other indications for laparotomy can often be managed nonoperatively, especially when the injury is further characterized by arteriography. (2) The absence of contrast extravasation on splenic arteriography seems to be a reliable predictor of successful nonoperative management. We suggest its use to triage CT-diagnosed splenic injuries to bed rest or intervention. (3) Coil embolization of the proximal splenic artery is an effective method of hemostasis in stabilized patients with splenic injury. It expands the number of patients who can be managed nonoperatively.

A proteomic study of serum from children with autism showing differential expression of apolipoproteins and complement proteins

Modern methods that use systematic, quantitative and unbiased approaches are making it possible to discover proteins altered by a disease. To identify proteins that might be differentially expressed in autism, serum proteins from blood were subjected to trypsin digestion followed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) on time-of-flight (TOF) instruments to identify differentially expressed peptides. Children with autism 4-6 years of age (n=69) were compared to typically developing children (n=35) with similar age and gender distributions. A total of 6348 peptide components were quantified. Of these, five peptide components corresponding to four known proteins had an effect size >0.99 with a P<0.05 and a Mascot identification score of 30 or greater for autism compared to controls. The four proteins were: Apolipoprotein (apo) B-100, Complement Factor H Related Protein (FHR1), Complement C1q and Fibronectin 1 (FN1). In addition, apo B-100 and apo A-IV were higher in children with high compared to low functioning autism. Apos are involved in the transport of lipids, cholesterol and vitamin E. The complement system is involved in the lysis and removal of infectious organisms in blood, and may be involved in cellular apoptosis in brain. Despite limitations of the study, including the low fold changes and variable detection rates for the peptide components, the data support possible differences of circulating proteins in autism, and should help stimulate the continued search for causes and treatments of autism by examining peripheral blood.

Peripheral blood gene expression profiling in rheumatoid arthritis

We carried out gene expression profiling of peripheral blood mononuclear cells (PBMCs) in 29 patients with active rheumatoid arthritis (RA) and 21 control subjects using Affymetrix U95Av2 arrays. Using cluster analysis, we observed a significant alteration in the expression pattern of 81 genes (P<0.001) in the PBMCs of RA patients compared with controls. Many of these genes correlated with differences in monocyte counts between the two study populations, and we show that a large fraction of these genes are specifically expressed at high levels in monocytes. In addition, a logistic regression analysis was performed to identify genes that performed best in the categorization of RA and control samples. Glutaminyl cyclase, IL1RA, S100A12 (also known as calgranulin or EN-RAGE) and Grb2-associated binding protein (GAB2) were among the top discriminators. Along with previous data, the overexpression of S100A12 in RA patients emphasizes the likely importance of RAGE pathways in disease pathogenesis. The altered expression of GAB2, an intracellular adaptor molecule involved in regulating phosphatase function, is of particular interest given the recent identification of the intracellular phosphatase PTPN22 as a risk gene for RA. These data suggest that a detailed study of gene expression patterns in peripheral blood can provide insight into disease pathogenesis. However, it is also clear that substantially larger sample sizes will be required in order to evaluate fully gene expression profiling as a means of identifying disease subsets, or defining biomarkers of outcome and response to therapy in RA.

A model for harmonizing flow cytometry in clinical trials

Complexities in sample handling, instrument setup and data analysis are barriers to the effective use of flow cytometry to monitor immunological parameters in clinical trials. The novel use of a central laboratory may help mitigate these issues.

Distinct mechanisms define murine B cell lineage immunoglobulin heavy chain (IgH) repertoires

Processes that define immunoglobulin repertoires are commonly presumed to be the same for all murine B cells. However, studies here that couple high-dimensional FACS sorting with large-scale quantitative IgH deep-sequencing demonstrate that B-1a IgH repertoire differs dramatically from the follicular and marginal zone B cells repertoires and is defined by distinct mechanisms. We track B-1a cells from their early appearance in neonatal spleen to their long-term residence in adult peritoneum and spleen. We show that de novo B-1a IgH rearrangement mainly occurs during the first few weeks of life, after which their repertoire continues to evolve profoundly, including convergent selection of certain V(D)J rearrangements encoding specific CDR3 peptides in all adults and progressive introduction of hypermutation and class-switching as animals age. This V(D)J selection and AID-mediated diversification operate comparably in germ-free and conventional mice, indicating these unique B-1a repertoire-defining mechanisms are driven by antigens that are not derived from microbiota.

DOI:http://dx.doi.org/10.7554/eLife.09083.001

Our immune system protects us by recognizing and destroying invading viruses, bacteria and other microbes. B cells are immune cells that produce protective proteins called antibodies to stop infections. These cells are activated by ‘antigens’, which are fragments of molecules from the microbes or from our own cells. When an antigen binds to a B cell, the cell matures, multiplies and produces proteins called antibodies. These antibodies can bind to the antigen, which marks the microbe for attack and removal by other cells in the immune system.

Each antibody consists of two ‘heavy chain’ and two ‘light chain’ proteins. B cells are able to produce a large variety of different antibodies due to the rearrangement of the gene segments that encode the heavy and light chains. In mice, there are two kinds of B cells – known as B-1a and B-2 cells – that play different roles in immune responses. B-1a cells have long been known to produce the ‘natural’ antibodies that are present in the blood prior to an infection. On the other hand, B-2 cells produce antibodies that are specifically stimulated by an infection and are better adapted to fighting it. Previous studies have shown that both types of antibodies are required to allow animals to successfully fight the flu virus.

Here, Yang, Wang et al. used a technique called fluorescence-activated cell sorting (or FACS) and carried out extensive genomic sequencing to study how the B-1a and B-2 populations rearrange their genes to produce heavy chains. This approach made it possible to separate the different types of B cells and then sequence the gene for the heavy chain within the individual cells. The experiments show that the “repertoire” of heavy chains in the antibodies of the B-1a cells is much less random and more repetitive than that of B-2 populations.

Furthermore, Yang, Wang et al. show that B-1a cells produce and maintain their repertoire of heavy chains in a different way to other B-2 populations. B-1a cells develop earlier and the major genetic rearrangements in the gene that encodes the heavy chain occur within the first few weeks of life. Although the gene rearrangements have mostly stopped by adulthood, the B-1a antibody repertoire continues to evolve profoundly as the B-1a cells divide over the life of the animal. On the other hand, the gene rearrangements that make the heavy chains in the B-2 cells continue throughout the life of the animal to produce the wider repertoire of antibodies found in these cells. In addition, the processes that continue to change the antibody reperotire in the B-1a cells during adulthood do not occur in the B-2 populations.

Importantly, the these reperotire-changing processes in B-1a cells also occur in mice that have been raised in germ-free conditions, which demonstrates that – unlike other B cells – the repertoire of heavy chains in B-1a cells is not influenced by antigens from microbes. Instead, it is mainly driven by antigens that are expressed by normal cells in the body. These findings open the way to future work aimed at understanding how B-1a cells help to protect us against infection, and their role in autoimmune diseases, where immune cells attack the body’s own healthy cells.

DOI:http://dx.doi.org/10.7554/eLife.09083.002

Femoral torsion after interlocked nailing of unstable femoral fractures

OBJECTIVE

The determination of rotation of the femur during intramedullary nailing procedures can be difficult, particularly when the fracture pattern does not lend itself to interdigitation. We studied 22 patients who had isolated femur fractures treated by closed intramedullary nailing to determine the degree of malrotation introduced at the time of surgery.

DESIGN AND METHODS

Anteversion of the affected and normal femora was determined by a standard computed tomography (CT) torsion study. The range of motion of the hip was measured in the prone position. Foot progression angles (FPAs) were measured in 14 patients who were fully ambulatory for at least 6 months.

MAIN RESULTS

The average malrotation of the fractured femur was 16 degrees (4 to 61 degrees). The median malrotation was 14 degrees. The differences in CT-measured anteversion (delta A), FPA (delta FPA), internal rotation (delta IR), and external rotation (delta ER) between the affected and normal sides were determined. Linear regression was used to analyze delta A with delta FPA, delta IR, and delta ER. Changes in internal and external rotation as determined by physical exam had a stronger correlation with delta A than did delta FPA. This indicates that malrotation of the femur is accommodated for during gait.

CONCLUSIONS

Based on this data, we found that anteversion of the normal femur can be determined in the operating room using the image intensifier and can be duplicated on the fractured side using the described technique in cases where comminution prevents fragmentational alignment. This method has been used for 12 patients in a prospective trial, and malrotation has been kept to under 10 degrees in all cases.

BX90: a new diamond anvil cell design for X-ray diffraction and optical measurements

We present a new design of a universal diamond anvil cell, suitable for different kinds of experimental studies under high pressures. Main features of the cell are an ultimate 90-degrees symmetrical axial opening and high stability, making the presented cell design suitable for a whole range of techniques from optical absorption to single-crystal X-ray diffraction studies, also in combination with external resistive or double-side laser heating. Three examples of the cell applications are provided: a Brillouin scattering of neon, single-crystal X-ray diffraction of α-Cr(2)O(3), and resistivity measurements on the (Mg(0.60)Fe(0.40))(Si(0.63)Al(0.37))O(3) silicate perovskite.

Interaction between LIS1 and doublecortin, two lissencephaly gene products

Mutations in either LIS1 or DCX are the most common cause for type I lissencephaly. Here we report that LIS1 and DCX interact physically both in vitro and in vivo. Epitope-tagged DCX transiently expressed in COS cells can be co-immunoprecipitated with endogenous LIS1. Furthermore, endogenous DCX could be co-immunoprecipitated with endogenous LIS1 in embryonic brain extracts, demonstrating an in vivo association. The two protein products also co-localize in transfected cells and in primary neuronal cells. In addition, we demonstrate homodimerization of DCX in vitro. Using fragments of both LIS1 and DCX, the domains of interaction were mapped. LIS1 and DCX interact with tubulin and microtubules. Our results suggest that addition of DCX and LIS1 to tubulin enhances polymerization in an additive fashion. In in vitro competition assays, when LIS1 is added first, DCX competes with LIS1 in its binding to microtubules, but when DCX is added prior to the addition of LIS1 it enhances the binding of LIS1 to microtubules. We conclude that LIS1 and DCX cross-talk is important to microtubule function in the developing cerebral cortex.

The ontogeny and functional characteristics of human B-1 (CD5+ B) cells

We demonstrate that, on average, greater than 90% of B lymphocytes in fetal spleen express CD5 at gestational ages of 17-23 weeks. Similarly, CD5+ B cells (B-1 cells) are the major B cell subset in umbilical cord blood. These findings depend on the optimization of fluorochrome conjugated anti-CD5 reagents for multiparameter fluorescent-activated cell sorter (FACS) analysis. From infancy through childhood the percentage of B-1 cells gradually diminishes in both spleen and peripheral blood. Stable adult levels, 25-35% of the total B cell population, are reached in late adolescence. The decrease in the percentage of B-1 cells in spleen is accompanied by an increase in conventional (CD5-) B cells, keeping the percentage of total B cells per mononuclear cells relatively constant. In contrast, in peripheral blood, the concentration of both B-1 cells and total B cells decreases, while T cells increase. At the functional level, we show that polyreactive IgM autoantibodies are produced by FACS-sorted CD5high B cells, but not by CD5- B cells from adolescent spleen. In contrast, fetal splenic CD5high and CD5- B cells appear functionally uniform, both producing IgM autoantibodies that are typical of B-1 cells. The apparent level of CD5- B cells in fetal spleen, on average 10% of total B cells, may still result from limitations of our reagent. The prominence of B-1 cells in fetal spleen and cord blood, the gradual reduction of B-1 cells with increasing age, and its characteristic repertoire, all suggest a role for this cell type in immunologically immature hosts.

Characteristics and development of the murine B-1b (Ly-1 B sister) cell population

In this paper we have outlined the evidence for two distinct branches of the B-1 cell lineage. The data show that phenotypically B-1a and B-1b cells are essentially identical, distinguished only by the presence or absence of the CD5 antigen. Functionally no differences between the two populations have yet been identified. Both produce anti-PtC antibodies, a specificity not observed in conventional B cells. Both produced high levels of IgM as measured in adoptive transfer experiments. Developmentally, B-1a and B-1b cells are indistinguishable with respect to generation from progenitors present in fetal liver and omentum, feedback regulation of new B-1a and B-1b cells from bone marrow, self-replenishment from Ig+ cells following adoptive transfer, and the generation of clonal populations. The major difference in the two populations is seen in the development of B-1a and B-1b cells from B220- progenitors in the adult bone marrow. Although B220- B-1a progenitors are rare in adult (greater than 6 weeks) bone marrow, the progenitors for B-1b cells persist well into adulthood. Our understanding of B-1b cell ontogeny is at a stage similar to that of B-1a cells five years ago. We have evidence from transfer experiments that strongly suggests the existence of two distinct progenitors for B-1a and B-1b, but we have yet to physically separate these progenitors as Solvansen et al. have done for B-1 and conventional B cells. Furthermore we must determine whether the B-1b cells that develop from fetal liver and bone marrow are functionally and developmentally equivalent to those that develop from adult bone marrow. As with B-1a cells, the role of B-1b cells in the immune system is unclear. Although we have not yet discerned functional differences between B-1a and B-1b, given the recent identification of CD72 (Lyb-2) as the ligand for CD5, it is tempting to speculate that B-1a cells are more involved in B-B cell interactions such as idiotype-anti-idiotype regulation of the early B-cell repertoire and that B-1b cells are more involved in B-T cell interactions. Whatever their function, it is clear that in trying to understand the role of the B-1 lineage it is important to consider both the B-1a and B-1b lineages.

De novo development and self-replenishment of B cells

Previous studies distinguished two murine B cell lineages: the conventional lineage, which comprises the majority of B cells, and the Ly-1 B lineage (B-1a), which represents a small percentage of total adult B cells. A third subset, B-1b cells, shares many properties with B-1a cells, including the characteristic ability to self-replenish, but does not express Ly-1 (CD5). Reconstitution studies presented here show that (i) although the B220- population in adult spleen and bone marrow contains very little progenitor activity for B-1a cells, it can reconstitute roughly half the normal number of B-1b cells; (ii) B-1 progenitors present in adult bone marrow and spleen function at low levels in adult animals; (iii) peritoneal B-1 cells (principally B-1b) that develop following bone marrow transfer, like B-1 cells from normal animals, are capable of substantial self-replenishment; and (iv) conventional B cells do not expand (self-replenish) in adoptive recipients, although they can persist for long periods. Collectively, these progenitor and self-replenishment characteristics provide a developmental base for distinguishing B-1a, B-1b and conventional B cells.

In search of cellular immunophenotypes in the blood of children with autism

BACKGROUND

Autism is a neurodevelopmental disorder characterized by impairments in social behavior, communication difficulties and the occurrence of repetitive or stereotyped behaviors. There has been substantial evidence for dysregulation of the immune system in autism.

METHODS

We evaluated differences in the number and phenotype of circulating blood cells in young children with autism (n = 70) compared with age-matched controls (n = 35). Children with a confirmed diagnosis of autism (4-6 years of age) were further subdivided into low (IQ<68, n = 35) or high functioning (IQ ≥ 68, n = 35) groups. Age- and gender-matched typically developing children constituted the control group. Six hundred and forty four primary and secondary variables, including cell counts and the abundance of cell surface antigens, were assessed using microvolume laser scanning cytometry.

RESULTS

There were multiple differences in immune cell populations between the autism and control groups. The absolute number of B cells per volume of blood was over 20% higher for children with autism and the absolute number of NK cells was about 40% higher. Neither of these variables showed significant difference between the low and high functioning autism groups. While the absolute number of T cells was not different across groups, a number of cellular activation markers, including HLA-DR and CD26 on T cells, and CD38 on B cells, were significantly higher in the autism group compared to controls.

CONCLUSIONS

These results support previous findings that immune dysfunction may occur in some children with autism. Further evaluation of the nature of the dysfunction and how it may play a role in the etiology of autism or in facets of autism neuropathology and/or behavior are needed.

Cy7PE and Cy7APC: bright new probes for immunofluorescence

We demonstrate the utility of indotricarbocyanine (Cy7) conjugates of the phycobiliproteins phycoerythrin (PE) and allophycocyanin (APC) in flow cytometry. This is the first demonstration of the use of an APC tandem dye for fluorescence measurements. These resonance energy transfer tandem dyes can be excited by the phycobiliprotein-specific excitation wavelengths and fluoresce at wavelengths above 780 nm. The tandem dyes, when conjugated to antibodies, are suitable for flow cytometry and other immunofluorescence applications. These conjugates are easily detectable above the very low autofluorescence in this part of the spectrum. Indeed, the Cy7-conjugated PE tandem (Cy7PE) has a "brightness" (fluorescence signal over cellular autofluorescence) comparable to that of fluorescein, and the Cy7APC tandem has a "brightness" comparable to that of APC. These tandems are also easily distinguished from other commonly used fluorophores, making them suitable for high-order multiparametric analysis. We show an example of six-color immunofluorescence analysis by flow cytometry, simultaneously measuring fluorescences from fluorescein, PE, Cy5PE, Texas red, APC, and Cy7APC.

Frequent occurrence of identical heavy and light chain Ig rearrangements

Single-cell PCR analyses of expressed Ig H and L chain sequences presented here show that certain rearrangements occur repeatedly and account for a major segment of the well-studied repertoire of B-1 cell autoantibodies that mediate the lysis of bromelain-treated mouse erythrocytes, i.e. antibodies reactive with phosphatldyicholine (PtC). We repeatedly isolated at least 10 different types of VH region rearrangements, involving three distinct germline genes, among FACS-sorted PtC-binding B-1 cells from three strains of mice (C57BL/6J, BALB/c and C.B-17). The predominant rearrangement, VH11-DSP-JH1 (VH11 type 1), has been previously found in anti-PtC hybridomas in several studies. We show that within each of six mice from two strains (C57BL/6J and BALB/c), unique instances of IgH/IgL pairing arose either from different B cell progenitors prior to IgH rearrangement or from pre-B cells which expanded after IgH rearrangement but prior to IgL rearrangement. Together with other recurrent rearrangements described here, our findings demonstrate that clonal expansion of mature B cells cannot account for all repeated rearrangements. As suggested by initial studies of dominant idiotype expression, these findings confirm that clonal expansion is only one of the mechanisms contributing to the establishment of recurrent rearrangements.

Evidence that intestinal IgA plasma cells in mu, kappa transgenic mice are derived from B-1 (Ly-1 B) cells

B6-Sp6 transgenic mice carry fully rearranged (BALB/c-derived, Igh-Ca allotype) mu heavy chain and kappa light chain transgenes, specific for trinitrophenyl, on a C57BL background (Igh-Cb allotype). FACS analyses show that the majority of B cells in peripheral lymphoid organs and bone marrow (BM) express transgenic IgM exclusively. A small proportion of the B cells, however, express endogenous IgM, usually concomitant with transgenic IgM. Three criteria establish that the endogenous IgM expressing B cells belong to the B-1 cell lineage. (i) Endogenous IgM expressing B cells in B6-Sp6 mice have the same localization pattern as B-1 cells from normal animals: they are enriched in the peritoneal cavity. (ii) The endogenous IgM+ B cells have the phenotype of B-1 cells: the endogenous IgM+ peritoneal B cells express Mac-1 (CD11b) and low levels of IgD, and most also express CD5 (Ly-1). (iii) B6-Sp6 BM poorly reconstitutes endogenous IgM+ B cells, just as adult BM from normal mice poorly reconstitutes B-1 cells. In contrast, B cells which only express the transgene are readily reconstituted by B6-Sp6 BM. The few endogenous IgM+ cells in the B6-Sp6 BM recipients are located in the peritoneal cavity and have the phenotype of B-1b cells (previously the Ly-1 B sister population), which are known to be reconstituted by adult BM. Two-color immunofluorescence staining of tissue sections from the gut and from isolated gut lamina propria cells shows the presence of many IgA containing cells, about one-third of which simultaneously express cytoplasmic (transgenic) IgM. The C-region of this IgA is produced by endogenous C alpha genes, because the transgene encodes only for C mu. Furthermore, the majority of gut IgA containing cells do not express the idiotype of the transgene, indicating that most of the gut IgA cells are encoded by endogenous VH genes and thus the result of an isotype switch from endogenous IgM expressing B cells. Since the endogenous IgM+ cells are B-1 cells (both B-1a and B-1b), the data strongly indicate that the intestinal IgA plasma cells also belong to the B-1 cell lineage.

Percutaneous insertion of the Kimray-Greenfield filter: incidence of femoral vein thrombosis

Venograms were obtained in 17 patients 5-8 days after percutaneous dilatation of the common femoral vein for insertion of the Kimray-Greenfield inferior vena cava filter. The venograms showed thrombosis of the common femoral vein in seven (41%) of the 17 patients, four of whom were symptomatic. Common femoral vein thrombosis can have serious clinical sequelae. The possibility of this complication should be considered before inserting the filter percutaneously via the femoral vein.

Superhard semiconducting optically transparent high pressure phase of boron

An orthorhombic (space group Pnnm) boron phase was synthesized at pressures above 9 GPa and high temperature, and it was demonstrated to be stable at least up to 30 GPa. The structure, determined by single-crystal x-ray diffraction, consists of B12 icosahedra and B2 dumbbells. The charge density distribution obtained from experimental data and ab initio calculations suggests covalent chemical bonding in this phase. Strong covalent interatomic interactions explain the low compressibility value (bulk modulus is K300=227 GPa) and high hardness of high-pressure boron (Vickers hardness HV=58 GPa), after diamond the second hardest elemental material.

B cell receptor and Toll-like receptor signaling coordinate to control distinct B-1 responses to both self and the microbiota

B-1a cells play an important role in mediating tissue homeostasis and protecting against infections. They are the main producers of 'natural' IgM, spontaneously secreted serum antibodies predominately reactive to self antigens, like phosphatidylcholine (PtC), or antigens expressed by the intestinal microbiota. The mechanisms that regulate the B-1a immunoglobulin (Ig) repertoire and their antibody secretion remain poorly understood. Here, we use a novel reporter mouse to demonstrate that production of self- and microbiota-reactive antibodies is linked to BCR signaling in B-1a cells. Moreover, we show that Toll-like receptors (TLRs) are critical for shaping the Ig repertoire of B-1a cells as well as regulating their antibody production. Strikingly, we find that both the colonization of a microbiota as well as microbial-sensing TLRs are required for anti-microbiota B-1a responses, whereas nucleic-acid sensing TLRs are required for anti-PtC responses, demonstrating that linked activation of BCR and TLRs controls steady state B-1a responses to both self and microbiota-derived antigens.

Cardiac Donor Risk Factors Predictive of Short-Term Heart Transplant Recipient Mortality: An Analysis of the United Network for Organ Sharing Database

INTRODUCTION

To address the shortage of donor hearts for transplantation, there is significant interest in liberalizing donor acceptance criteria. Therefore, the aim of this study was to evaluate cardiac donor characteristics from the United Network for Organ Sharing (UNOS) database to determine their impact on posttransplantation recipient outcomes.

METHODS

Adult (≥18 years) patients undergoing heart transplantation from July 1, 2004, to December 31, 2012, in the UNOS Standard Transplant Analysis and Research (STAR) database were reviewed. Patients were stratified by 1-year posttransplantation status; survivors (group S, n = 13,643) and patients who died or underwent cardiac retransplantation at 1-year follow-up (group NS/R = 1785). Thirty-three specific donor variables were collected for each recipient, and independent donor predictors of recipient death or retransplantation at 1 year were determined using multivariable logistic regression analysis.

RESULTS

Overall 1-year survival for the entire cohort was 88.4%. Mean donor age was 31.5 ± 11.9 years, and 72% were male. On multivariable logistic regression analysis, donor age >40 years (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.27 to 1.64), graft ischemic time >3 hours (OR 1.32, 1.16 to 1.51), and the use of cardioplegia (OR 1.17, 1.01 to 1.35) or Celsior (OR 1.21, 1.06 to 1.38) preservative solution were significant predictors of recipient death or retransplantation at 1 year posttransplantation. Male donor sex (OR 0.83, 0.74 to 0.93) and the use of antihypertensive agents (OR 0.88, 0.77 to 1.00) or insulin (OR 0.84, 0.76 to 0.94) were protective from adverse outcomes at 1 year.

CONCLUSIONS

These data suggest that donors who are older, female, or have a long projected ischemic time pose greater risk to heart transplant recipients in the short term. Additionally, certain components of donor management protocols, including antihypertensive and insulin administration, may be protective to recipients.