Search PubMed⌕ Search

Biomedical subjects

C A Janeway

Publications and source records attributed to C A Janeway.

At least 37 records · Page 2Linked to original sources
PubMed2000

Relapsing and remitting experimental autoimmune encephalomyelitis in B cell deficient mice.

Experimental autoimmune encephalomyelitis (EAE) is an animal model for the human autoimmune central nervous system (CNS) disease multiple sclerosis (MS). To examine the role of B cells in EAE with a relapsing and remitting disease course (R-EAE) we generated (B10.PL x SJL/J)F1 mice deficient in B cells by disrupting their mu heavy chain transmembrane region (B10.PL x SJL/J)F1 muMT-/-. By immunizing (B10.PL x SJL/J)F1 and (B10.PL x SJL/J)F1 muMT-/- mice with the encephalitogenic N-terminal peptide Acl-11 of myelin basic protein (MBP), we observed that B-cell deficient mice exhibited a relapsing and remitting disease course. Since a similar day of onset and day of first relapse were observed these data suggest that B cells do not play a vital role in the activation of T cells leading to the initiation of EAE, nor in the reactivation of T cells resulting in R-EAE.

Amino Acid Sequence↗
PubMed2000

An islet-specific CD8+ T cell hybridoma generated from non-obese diabetic mice recognizes insulin as an autoantigen.

Although CD8+ T cells play a major role in beta cell destruction in insulin-dependent diabetes in the non-obese diabetic mouse, the T cell autoantigen(s) recognized by such cells remains to be identified. Therefore, an islet-reactive, CD8+ T cell line was generated from islet-infiltrating cells and hybridized by fusion with a CD8+ alphabeta TCR- BW5147 thymoma. In the presence of islets, none of the 12 CD3+ CD8+ T cell hybridomas isolated secreted IL-2/IL-4 or IFNgamma but three were islet specific, as shown by activation induced cell death. Subclone 4A7.7.15 recognized only islets expressing H-2Kd, demonstrated islet-specific inhibition of proliferation and concomitant partial arrest in the G2/M phase of the cell cycle. Further analysis using a panel of cell lines, expressing H-2Kd, and transfected with the cDNA for various putative autoantigens in type 1 diabetes showed that 4A7.7.15 recognizes insulin as an antigen.

Animals↗
PubMed2000

Differential adhesion molecule requirements for immune surveillance and inflammatory recruitment.

Activated CD4 Th1 lymphocytes can enter the brain in the absence of an inflammatory focus. However, the molecular mediators that regulate this early migration of lymphocytes into the brain have remained unclear. We hypothesized that the entry of these 'pioneer' lymphocytes into the brain is regulated by a set of molecular events that are distinct from those used once inflammation has been established. Using cells fluorescently labelled with the lipophilic dye DiI, myelin basic protein (MBP)-specific CD4 lymphocytes that expressed low or high levels of very late antigen-4 (VLA-4) and non-antigen-specific activated splenocytes homed to mouse brain in similar quantities 2 h after adoptive transfer. However, antigen specificity and VLA-4 expression were required for more robust recruitment by 24 h. Immunocytochemistry revealed endothelial and microenvironmental upregulation of vascular cell adhesion molecule (VCAM), intercellular cell adhesion molecule 1 (ICAM-1), MHC class II and interferon-gamma 48 h after transfer of MBP-specific cells. In contrast, expression of meningeal and choroid plexus-associated P selectin was upregulated 2 h after adoptive transfer, but not at 48 h. Monoclonal antibody to P selectin, but not to VLA-4, inhibited early migration of high VLA-4-expressing MBP-specific lymphocytes. These results suggest that early migration occurs independent of the lymphocyte integrin VLA-4 and endothelial VCAM, but does require increased surface expression of endothelial P selectin.

Animals↗
PubMed1999

Lipoproteins take their toll on the host.

A family of mammalian Toll-like receptors (TLRs) has a critical role in the recognition of microbial infection. Recent evidence suggests that bacterial lipoproteins - major components of bacterial cell walls - are recognized by a member of the human TLR family.

Animals↗
PubMed1999

Alpha(1,3)-fucosyltransferase VII and alpha(2,3)-sialyltransferase IV are up-regulated in activated CD4 T cells and maintained after their differentiation into Th1 and migration into inflammatory sites.

Activated Th1 CD4 T cells bind to P-selectin and migrate into inflamed tissue, whereas Th2 cells do not. We show that alpha(1, 3)-fucosyltransferase VII (FucT-VII) and alpha(2, 3)-sialyltransferase IV (ST3GalIV), which are crucial for the biosynthesis of functional P-selectin ligands, are absent in naive CD4 T cells, but are rapidly up-regulated upon activation. Th1 or Th2 differentiation in the presence of polarizing cytokines leads to down-regulation of FucT-VII mRNA selectively in Th2 but not in Th1 cells. Influencing the differentiation by varying the priming dose of antigenic peptide results in similar FucT-VII down-regulation only in Ag-specific Th2 cells. ST3GalIV levels remain elevated. FucT-VII and ST3GalIV mRNAs are also up-regulated by Th1 cells primed in vivo and recruited into the lymph nodes draining delayed-type hypersensitivity sites. We identify FucT-VII gene expression as a principal difference between Th1 and Th2 cells, and underscore the importance of FucT-VII and ST3GalIV expression for the biosynthesis of functional selectin ligands.

Animals↗
PubMed1999

Development of CD8alpha/alpha and CD8alpha/beta T cells in major histocompatibility complex class I-deficient mice.

Peripheral CD8(+) T cells mainly use CD8alpha/beta, and their development is mainly dependent on the major histocompatibility complex (MHC) class I proteins K(b) and D(b) in H-2(b) mice. In this report, we have shown that the development of CD8alpha/beta TCR-alpha/beta cells in lymphoid organs as well as in intestinal intraepithelial lymphocytes (iIELs) is dependent on the MHC class I K(b) and D(b) proteins. In contrast, TCR-alpha/beta CD8alpha/alpha cells are found mainly in iIELs, and their numbers are unaffected in K(b)D(b) double knockout mice. Most of the TCR-gamma/delta cells in the iIELs also bear CD8alpha/alpha, and they are also unaffected in K(b)D(b) -/- mice. In beta2-microglobulin (beta2m)-deficient mice, all of the TCR-alpha/beta CD8alpha/alpha and CD8alpha/beta T cells disappear, but TCR-gamma/delta cells are unaffected by the absence of beta2m.

Animals↗
PubMed1999

ECSIT is an evolutionarily conserved intermediate in the Toll/IL-1 signal transduction pathway.

Activation of NF-kappaB as a consequence of signaling through the Toll and IL-1 receptors is a major element of innate immune responses. We report the identification and characterization of a novel intermediate in these signaling pathways that bridges TRAF6 to MEKK-1. This adapter protein, which we have named ECSIT (evolutionarily conserved signaling intermediate in Toll pathways), is specific for the Toll/IL-1 pathways and is a regulator of MEKK-1 processing. Expression of wild-type ECSIT accelerates processing of MEKK-1, whereas a dominant-negative fragment of ECSIT blocks MEKK-1 processing and activation of NF-kappaB. These results indicate an important role for ECSIT in signaling to NF-kappaB and suggest that processing of MEKK-1 is required for its function in the Toll/IL-1 pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Presentation of the self antigen myelin basic protein by dendritic cells leads to experimental autoimmune encephalomyelitis.

Bone marrow (BM)-derived dendritic cells (DC) are potent stimulators of naive CD4+ T cell activation. Because DC are efficient at Ag processing and could potentially present self Ags, we investigated the role of DC in the presentation of an encephalitogenic peptide from myelin basic protein (Ac1-11) in the induction of experimental autoimmune encephalomyelitis (EAE). To determine if DC could prime for EAE, we transferred DC pulsed with Ac1-11 or with medium alone into irradiated mice in combination with CD4+ T cells isolated from a mouse transgenic for a TCR specific for Ac1-11 + I-Au. Mice transferred with Ac1-11-pulsed DC developed EAE 7-10 days later, whereas mice receiving medium-pulsed DC did not. By day 15, all mice given peptide-loaded DC had signs of tail and hind limb paralysis, and by day 20 infiltration of Ac1-11-specific CD4+ T cells was detected in the brain parenchyma. We also demonstrated interactions between Ac1-11-pulsed DC and Ac1-11-specific T cells in the lymph nodes 24 h following adoptive transfer of both cell populations. These data show that DC can efficiently present the self Ag myelin basic protein Ac1-11 to Ag-specific T cells in the periphery of mice to induce EAE.

Amino Acid Sequence↗
PubMed1999

Evidence for Fas-dependent and Fas-independent mechanisms in the pathogenesis of experimental autoimmune encephalomyelitis.

To determine whether Fas or Fas ligand (FasL) plays a role in susceptibility to experimental autoimmune encephalomyelitis (EAE), we bred a TCR transgenic mouse specific for the Ac1-11 peptide of myelin basic protein to mice with inactivating mutations in Fas (lpr) or FasL (gld). Disease induction by peptide immunization in such mice produced similar disease scores, demonstrating that Fas/FasL interactions were not necessary to generate EAE. However, adoptive transfer experiments showed evidence that these interactions can play a role in the pathogenesis of EAE, shown most dramatically by the absence of disease following transfer of cells from a normal myelin basic protein TCR transgenic mouse into a Fas-deficient lpr recipient. Furthermore, transfer of cells lacking FasL (gld) into normal or gld recipients gave a diminished disease score. Thus, Fas/FasL interactions can play a role in the pathogenesis of EAE, but they are not required for disease to occur.

Adoptive Transfer↗
PubMed1999

Phylogenetic perspectives in innate immunity.

The concept of innate immunity refers to the first-line host defense that serves to limit infection in the early hours after exposure to microorganisms. Recent data have highlighted similarities between pathogen recognition, signaling pathways, and effector mechanisms of innate immunity in Drosophila and mammals, pointing to a common ancestry of these defenses. In addition to its role in the early phase of defense, innate immunity in mammals appears to play a key role in stimulating the subsequent, clonal response of adaptive immunity.

Animals↗
PubMed1999

T-cell development: a role for self-peptides in positive selection.

An important issue for immunologists is the difference between the two main processes that determine the mature repertoire of T-cell receptors, termed positive and negative selection. Recent papers have addressed the role of self-peptides in the process of positive selection.

Animals↗
PubMed1999

STAT5 interaction with the T cell receptor complex and stimulation of T cell proliferation.

The role of STAT (signal transducer and activator of transcription) proteins in T cell receptor (TCR) signaling was analyzed. STAT5 became immediately and transiently phosphorylated on tyrosine 694 in response to TCR stimulation. Expression of the protein tyrosine kinase Lck, a key signaling protein in the TCR complex, activated DNA binding of transfected STAT5A and STAT5B to specific STAT inducible elements. The role of Lck in STAT5 activation was confirmed in a Lck-deficient T cell line in which the activation of STAT5 by TCR stimulation was abolished. Expression of Lck induced specific interaction of STAT5 with the subunits of the TCR, indicating that STAT5 may be directly involved in TCR signaling. Stimulation of T cell clones and primary T cell lines also induced the association of STAT5 with the TCR complex. Inhibition of STAT5 function by expression of a dominant negative mutant STAT5 reduced antigen-stimulated proliferation of T cells. Thus, TCR stimulation appears to directly activate STAT5, which may participate in the regulation of gene transcription and T cell proliferation during immunological responses.

Animals↗
PubMed1999

Characterization of a novel human surface molecule selectively expressed by mature thymocytes, activated T cells and subsets of T cell lymphomas.

We have previously characterized mouse H4 (mH4), a surface glycoprotein recognized by the C398.4A monoclonal antibody. We now show that C398.4A also binds its human putative homolog (hpH4). Both hpH4 and mH4 (1) are selectively expressed by activated T cells and mature thymocytes, (2) are disulfide-linked dimers of two chains (29/37 kDa in humans, 25/29 kDa in mice), whose N-deglycosylation produces a single band at 20 - 21 kDa, and (3) display a low association with CD4 and the TCR. The expression pattern of hpH4 and its biochemical features showed that it is different from other known activation molecules, and this was confirmed when analysis of the tryptic digest of the hpH4 29-kDa band by peptide mass searching using matrix-assisted laser desorption ionization mass spectrometry did not reveal any significant homology with other molecules. In normal lymphoid tissue, hpH4 is expressed by T cells located at the periphery of lymph node germinal centers and paracortical areas. In T cell neoplasia, expression of hpH4 clusters with a subset of peripheral T cell lymphomas with a large-cell component, and with cases of angioimmunoblastic T cell lymphomas. Overall, these data provide evidence for a novel T cell activation molecule that could help in the phenotypic categorization of T cell malignancies.

Animals↗
PubMed1999

Immunology at Yale.

Explore the source record for details and available documents.

Allergy and Immunology↗
PubMed1999

The role of self-recognition in receptor repertoire development. Members of the Janeway Laboratory.

The role of self-antigen recognition in the development of T and B cells of the adaptive immune system has been studied in several different ways. We have shown that CD4 T cells are selected on self-peptide:self-MHC class II ligands, and in the periphery, they are sustained by contact with the same or similar ligands. We have also observed that B cells are positively selected on unknown and presumed self-ligands. We have used this information to explore autoimmune diseases as well. Finally, we have recently identified the innate immune system as playing a crucial role in regulating expression of costimulatory molecules that are required for induction of adaptive immune responses.

Animals↗