bluuebunny/crossref_metadata_2025 huggingface dataset:
T helper phenotype and genetic susceptibility in experimental Lyme disease.
Authors: Matyniak J E , Reiner S L
Published: June 2004

Infection of inbred mice with Borrelia burgdorferi results in strain-specific variation in the severity of pathogen-induced arthritis: BALB/c mice develop only mild disease whereas C3H/HeJ mice develop severe arthritis. The immunologic basis for varying host susceptibility has yet to be defined. We modified experimental Lyme disease to facilitate measurement of antigen-specific cytokine production in resistant and susceptible mice. The analysis revealed highly polarized lymphokine patterns directly linked to differing disease outcomes. Among the inbred strains of mice challenged with B. burgdorferi, production of interleukin 4 (IL-4) correlated to resistance whereas production of interferon gamma (IFN-gamma) correlated to susceptibility. We also demonstrate that production of IL-4 or IFN-gamma regulates the severity of arthritis after infection. Neutralization of IL-4 in resistant BALB/c mice resulted in more severe arthritis whereas neutralization of IFN-gamma in susceptible C3H/HeJ mice attenuated the severity of disease. These results suggest a primary relationship between T helper cell phenotype and the genetic basis for susceptibility to experimental Lyme borreliosis.
Pocket 4 of the HLA-DR(α,β 1*0401) molecule is a major determinant of T cells recognition of peptide.
Authors: Fu X T , Bono C P , Woulfe S L , Swearingen C , Summers N L , Sinigaglia F , Sette A , Schwartz B D , Karr R W
Published: June 2004

To investigate the functional roles of individual HLA-DR residues in T cell recognition, transfectants expressing wild-type or mutant DR(alpha,beta 1*0401) molecules with single amino acid substitutions at 14 polymorphic positions of the DR beta 1*0401 chain or 19 positions of the DR alpha chain were used as antigen-presenting cells for five T cell clones specific for the influenza hemagglutinin peptide, HA307-19. Of the six polymorphic positions in the DR beta floor that were examined, mutations at only two positions eliminated T cell recognition: positions 13 (four clones) and 28 (one clone). In contrast, individual mutations at DR beta positions 70, 71, 78, and 86 on the alpha helix eliminated recognition by each of the clones, and mutations at positions 74 and 67 eliminated recognition by four and two clones, respectively. Most of the DR alpha mutations had minimal or no effect on most of the clones, although one clone was very sensitive to changes in the DR alpha chain, with loss of recognition in response to 10 mutants. Mutants that abrogated recognition by all of the clones were assessed for peptide binding, and only the beta 86 mutation drastically decreased peptide binding. Single amino acid substitutions at polymorphic positions in the central part of the DR beta alpha helix disrupted T cell recognition much more frequently than substitutions in the floor, suggesting that DR beta residues on the alpha helix make relatively greater contributions than those in the floor to the ability of the DR(alpha,beta 1*0401) molecule to present HA307-19. The data indicate that DR beta residues 13, 70, 71, 74, and 78, which are located in pocket 4 of the peptide binding site in the crystal structure of the DR1 molecule, exert a major and disproportionate influence on the outcome of T cell recognition, compared with other polymorphic residues.
A subset of CD4+ memory T cells contains preformed CD40 ligand that is rapidly but transiently expressed on their surface after activation through the T cell receptor complex.
Authors: Casamayor-Palleja M , Khan M , MacLennan I C
Published: June 2004

Signaling through surface CD40 is essential for selecting B cells that have mutated their immunoglobulin variable region genes in germinal centers and is an important signal in the early stages of antibody responses to T cell-dependent antigens. It is shown that a subset of CD45RO+, CD4+ T cells isolated from human tonsil contains preformed 30-35-kD ligand for CD40. This is expressed on their surfaces within 5 min of their antigen-receptor complexes interacting with CD3 epsilon antibodies bound to ox erythrocytes. This surface expression does not require de novo protein synthesis and lasts for only 1-2 h. Preformed CD40 ligand (CD40L) was not detected in any CD4+ CD45RA+ T cells, but > 90% of all CD4+ T cells from the tonsil can be induced to express large amounts of CD40L on culture with phorbol myristate acetate and the calcium ionophore ionomycin. This expression of CD40L starts between 1 and 2 h, peaks at 6 h, and remains at a high level for > 20 h. It is totally prevented by adding a concentration of cycloheximide that inhibits CD25 synthesis by these activated cells. While CD3 epsilon antibody bound to ox red cells is a good inducer of surface expression of CD40L, it is a much less potent inducer of CD40L synthesis than phorbol myristate acetate with ionomycin. Immunohistological analysis of tonsil sections shows that cells containing CD40L are located mainly in the outer zone of germinal centers and the margins of the T zones that are rich in dendritic cells (interdigitating cells). The distribution of these cells is consistent with: (a) their interaction in T zones with B cells that have taken up and processed antigen and (b) their involvement in B cell selection in germinal centers.
Facultative role of germinal centers and T cells in the somatic diversification of IgVH genes.
Authors: Miller C , Stedra J , Kelsoe G , Cerny J
Published: June 2004

The development of memory B cells takes place in germinal centers (GC) of lymphoid follicles where antigen-driven lymphocytes undergo somatic hypermutation and affinity selection, presumably under the influence of helper T cells. However, the mechanisms that drive this complex response are not well understood. We explored the relationship between GC formation and the onset of hypermutation in response to the hapten phosphorylcholine (PC) coupled to antigenic proteins in mice bearing different frequencies of CD4+ T cells. PC-reactive GC were identified by staining frozen splenic sections with peanut agglutinin (PNA) and with monoclonal Abs against AB1-2, a dominant idiotope of T15+ anti-PC antibody. The nucleotide sequences of rearranged T15 VH1 genes were determined from polymerase chain reaction amplifications of genomic DNA from microdissected GC B cells. T15+ GC became fully developed by day 6-7 after primary immunization of euthymic mice with either PC-keyhole limpet hemocyanin (KLH) or PC-chicken gamma globulin (CGG). Yet the VH1 gene segments recovered from the primary GC as late as day 10-14 had low numbers of mutations, in contrast to responses to the haptens nitrophenyl or oxazolone that sustain high levels of hypermutation after GC formation. PC-reactive B cells proliferate in histologically typical GC for considerable periods with no or little somatic hypermutation; the signals for GC formation are independent of those for the activation of hypermutation. We then examined GC 7 d after secondary immunization with PC-KLH in euthymic mice, in nu/nu mice reconstituted with limited numbers of normal CD4+ cells before priming (CD4(+)-nu/nu) and in nu/nu mice. All of these animals develop T15+ GC after antigen priming, however, the patterns of V gene mutations in the secondary GC reflected the levels of CD4+ cells present during the primary response. VDJ sequences from secondary GC of euthymic mice were heavily mutated, but most of these mutations were shared among all related (identical VDJ joints) sequences suggesting the proliferation of mutated, memory B cells, with little de novo somatic hypermutation. In contrast, the patterns of V gene diversity in secondary GC from CD4(+)-nu/nu mice suggested that there was ongoing mutation and clonal diversification during the first week after rechallenge. The secondary GC from T cell-deficient, nu/nu mice showed little evidence for mutational and/or recombinational diversity of T15+ B cells. We conclude that the participation of CD4+ helper cells is required for full activation of the mutator in GC and takes place in a dose-dependent fashion.
Processing of major histocompatibility class I-restricted antigens in the endoplasmic reticulum.
Authors: Elliott T , Willis A , Cerundolo V , Townsend A
Published: June 2004

We have introduced long precursor peptides directly into the endoplasmic reticulum (ER) of a mutant cell line (T2-Db) that lacks the ability to transport peptides from the cytosol to the ER in a transporter associated with antigen processing (TAP) dependent way. This was done by expressing various influenza A-derived peptides containing the naturally processed epitope ASNENMDAM (366-374) preceded by the influenza hemagglutinin ER translocation sequence. Peptides derived from these minigenes that became associated with Db were isolated and identified by combined reversed phase liquid chromatography and detection by cytotoxic T lymphocytes. Our results establish that NH2-terminal extensions of at least 40 residues can be trimmed from peptides entering the ER, but that proteolysis of larger proteins may be limited.
Pancreatic islet beta cells drive T cell-immune responses in the nonobese diabetic mouse model.
Authors: Larger E , Bécourt C , Bach J F , Boitard C
Published: June 2004

The role of autoantigens and that of target organs in which tissue lesions develop remains elusive in most spontaneous models of autoimmune diseases. Whether the presence of target autoantigens is required for the recruitment of autoreactive lymphocytes is unknown in most cases. To evaluate the importance of islet cells in the development of autoimmunity in the nonobese diabetic (NOD) mouse, we generated beta cell-deprived mice by injecting a high dose of alloxan, a toxic agent specific for beta cells. In contrast with spleen cells from 6-mo-old naive NOD mice which transfer diabetes in irradiated 8-mo-old male recipients, spleen cells from age-matched NOD mice which received a single injection of alloxan at 3 wk of age did not transfer diabetes. With the exception of the ability to transfer diabetes, beta cell-deprived NOD mice showed maintained immune competence. Furthermore, sialitis developed with the expected intensity and prevalence in beta cell-deprived mice. Already committed "diabetogenic" spleen cells collected from spontaneously diabetic mice also showed a reduced capacity to transfer diabetes after their removal from the diabetic mice and transient "parking" in beta cell-deprived mice. Taken together, our data bring evidence that involvement of autoreactive T cells detected by the capacity to transfer diabetes requires the presence of target beta cells.
Reduction in mitochondrial potential constitutes an early irreversible step of programmed lymphocyte death in vivo.
Authors: Zamzami N , Marchetti P , Castedo M , Zanin C , Vayssière J L , Petit P X , Kroemer G
Published: June 2004

In a number of experimental systems in which lymphocyte depletion was induced by apoptosis-inducing manipulations, no apoptotic morphology and ladder-type DNA fragmentation were detected among freshly isolated peripheral lymphocytes ex vivo. Here we report that one alteration that can be detected among splenocytes stimulated with lymphocyte-depleting doses of dexamethasone (DEX) in vivo is a reduced uptake of 3,3'dihexyloxacarbocyanine iodide (DiOC6[3]), a fluorochrome which incorporates into cells dependent upon their mitochondrial transmembrane potential (delta psi m). In contrast, ex vivo isolated splenocytes still lacked established signs of programmed cell death (PCD):DNA degradation into high or low molecular weight fragments, ultrastructural changes of chromatin arrangement and endoplasmatic reticulum, loss in viability, or accumulation of intracellular peroxides. Moreover, no changes in cell membrane potential could be detected. A reduced delta psi m has been observed in response to different agents inducing lymphoid cell depletion in vivo (superantigen and glucocorticoids [GC]), in mature T and B lymphocytes, as well as their precursors. DEX treatment in vivo, followed by cytofluorometric purification of viable delta psi mlow splenic T cells ex vivo, revealed that this fraction of cells is irreversibly committed to undergoing DNA fragmentation. Immediately after purification neither delta psi mlow, nor delta psi mhigh cells, exhibit detectable DNA fragmentation. However, after short-term culture (37 degrees C, 1 h) delta psi mlow cells show endonucleolysis, followed by cytolysis several hours later. Incubation of delta psi mlow cells in the presence of excess amount of the GC receptor antagonist RU38486 (which displaces DEX from the GC receptor), cytokines that inhibit DEX-induced cell death, or cycloheximide fails to prevent cytolysis. The antioxidant, N-acetylcysteine, as well as linomide, an agent that effectively inhibits DEX or superantigen-induced lymphocyte depletion in vivo, also stabilize the DiOC6(3) uptake. In contrast, the endonuclease inhibitor, aurintricarboxylic acid acts at later stages of apoptosis and only retards the transition from the viable delta psi mlow to the nonviable fraction. Altogether, these data suggest a sequence of PCD-associated events in which a reduction in delta psi m constitutes an obligate irreversible step of ongoing lymphocyte death, preceding other alterations of cellular physiology, and thus allowing for the ex vivo assessment of PCD.
Soluble CD14 acts as a shuttle in the neutralization of lipopolysaccharide (LPS) by LPS-binding protein and reconstituted high density lipoprotein.
Authors: Wurfel M M , Hailman E , Wright S D
Published: June 2004

We have recently shown that lipopolysaccharide (LPS)-binding protein (LBP) is a lipid transfer protein that catalyzes two distinct reactions: movement of bacterial LPS (endotoxin) from LPS micelles to soluble CD14 (sCD14) and movement of LPS from micelles to reconstituted high density lipoprotein (R-HDL) particles. Here we show that LBP facilitates a third lipid transfer reaction: movement of LPS from LPS-sCD14 complexes to R-HDL particles. This action of LBP is catalytic, with one molecule of LBP enabling the movement of multiple LPS molecules into R-HDL. LBP-catalyzed movement of LPS from LPS-sCD14 complexes to R-HDL neutralizes the capacity of LPS to stimulate polymorphonuclear leukocytes. Our findings show that LPS may be transferred to R-HDL either by the direct action of LBP or by a two-step reaction in which LPS is first transferred to sCD14 and subsequently to R-HDL. We have observed that the two-step pathway of LPS transfer to R-HDL is strongly favored over direct transfer. Neutralization of LPS by LBP and R-HDL was accelerated more than 30-fold by addition of sCD14. Several observations suggest that sCD14 accelerates this reaction by serving as a shuttle for LPS: addition of LBP and sCD14 to LPS micelles resulted in LPS-sCD14 complexes that could diffuse through a 100-kD cutoff filter; LPS-sCD14 complexes appeared transiently during movement of LPS to R-HDL facilitated by purified LBP; and sCD14 could facilitate transfer of LPS to R-HDL without becoming part of the final LPS-R-HDL complex. Complexes of LPS and sCD14 were formed transiently when LPS was incubated in plasma, suggesting that these complexes may play a role as intermediates in the neutralization of LPS under physiological conditions. These findings detail a new activity for sCD14 and suggest a novel mechanism for lipid transfer by LBP.
Interleukin 12 signaling in T helper type 1 (Th1) cells involves tyrosine phosphorylation of signal transducer and activator of transcription (Stat)3 and Stat4.
Authors: Jacobson N G , Szabo S J , Weber-Nordt R M , Zhong Z , Schreiber R D , Darnell J E , Murphy K M
Published: June 2004

Interleukin 12 (IL-12) initiates the differentiation of naive CD4+ T cells to T helper type 1 (Th1) cells critical for resistance to intracellular pathogens such as Leishmania major. To explore the basis of IL-12 action, we analyzed induction of nuclear factors in Th1 cells. IL-12 selectively induced nuclear DNA-binding complexes that contained Stat3 and Stat4, recently cloned members of the family of signal transducers and activators of transcription (STATs). While Stat3 participates in signaling for several other cytokines, Stat4 was not previously known to participate in the signaling pathway for any natural ligand. The selective activation of Stat4 provides a basis for unique actions of IL-12 on Th1 development. Thus, this study presents the first identification of the early events in IL-12 signaling in T cells and of ligand activation of Stat4.
The intracellular signal transduction mechanism of interleukin 5 in eosinophils: the involvement of lyn tyrosine kinase and the Ras-Raf-1-MEK-microtubule-associated protein kinase pathway.
Authors: Pazdrak K , Schreiber D , Forsythe P , Justement L , Alam R
Published: June 2004

Interleukin 5 (IL-5) regulates the growth and function of eosinophils. The objective of this study was to investigate the intracellular signal transduction mechanism of IL-5 in eosinophils. Purified eosinophils were stimulated with IL-5, and the involvement of various kinases was investigated by immunoblotting, immune complex kinase assay, and in situ denatured/renatured kinase assay. We found that IL-5 induced tyrosine phosphorylation and activation of a number of kinases. Two species of lyn kinases (53 and 56 kD) were present in eosinophils. Both forms were Tyr-phosphorylated and activated rapidly within 1 min. Further, lyn kinase was physically associated with the IL-5 beta receptor in eosinophils. Ras was studied by immunoprecipitation followed by thin-layer chromatography. Ras bound higher quantities of [alpha-32P]guanosine 5'triphosphate upon stimulation with IL-5. Raf-1 kinase showed increased Tyr phosphorylation on immunoblotting and increased activity in the immune complex kinase assay. Two species of MEK (MAP or Erk kinase) (41 and 45 kD) were identified in eosinophils, which underwent autophosphorylation upon stimulation. Microtubule-associated protein (MAP) kinase (p44) was Tyr-phosphorylated on immunoblotting and had increased activity in the immune-complex kinase assay. MAP kinases were also studied after metabolic radiolabeling of the cells with [32P]orthophosphates. IL-5 stimulated phosphorylation of MAP kinases in situ. Thus, we have delineated major components of an important signaling pathway in eosinophils. We believe that one of the signals generated by IL-5 receptor activation is propagated through the lyn-Ras-Raf-1-MEK-MAP kinase pathway.
T cell receptor repertoire in polymyositis: clonal expansion of autoaggressive CD8+ T cells.
Authors: Bender A , Ernst N , Iglesias A , Dornmair K , Wekerle H , Hohlfeld R
Published: June 2004

In polymyositis (PM), CD8+ T cell receptor (TCR) alpha/beta + cells invade and destroy major histocompatibility complex class I-positive muscle fibers. We combined polymerase chain reaction (PCR) and double-fluorescence immunocytochemistry to analyze the T cell receptor (TCR) repertoire expressed in muscle of PM patients. In patient 1, inverse PCR revealed a preferential usage of TCR V alpha 33.1, V beta 13.1, and V beta 5.1. Six of six TCR V alpha 33.1+ clones and five of seven V beta 13.1+ clones had identical nucleotide sequences. In contrast, the V beta 5.1+ TCRs were more heterogeneous. Similar results were obtained with an independent PCR method using primers specific for TCR V alpha 33, V beta 13, or V beta 5. No TCR sequences could be amplified from noninflammatory control muscle. Furthermore, none of the TCR sequences found in PM muscle could be detected in blood from the same patient or from a normal control subject. Immunohistochemistry confirmed that V beta 5.1 and V beta 13.1 were overrepresented in the muscle lesions of this patient. 32% of all CD8+ T cells were V beta 13.1+, and 16% were V beta 5.1+. However, approximately 60% of the CD8+ T cells that invaded muscle fibers were V beta 13.1+, whereas 10% were V beta 5.1+. In patient 2, 50% of the T cells were V beta 5.1+, and as in patient 1, these T cells were mainly located in interstitial areas. In patient 3, > 75% of the autoinvasive T cells stained with an anti-V beta 3 mAb. Sequence analysis of 15 PCR clones amplified with a V beta 3-specific primer showed that 9 (60%) sequences were identical. The results suggest that (a) a strikingly limited TCR repertoire is expressed in PM muscle; (b) there is a dissociation between the TCR usage of autoinvasive and interstitial T cells; and (c) the autoinvasive T cells are clonally expanded.
NKR-P1A is a target-specific receptor that activates natural killer cell cytotoxicity.
Authors: Ryan J C , Niemi E C , Nakamura M C , Seaman W E
Published: June 2004

NKR-P1A is a lectinlike surface molecule expressed on rat natural killer (NK) cells. NKR-P1A has structural and functional features of an activating NK cell receptor, but a requirement for NKR-P1A in target cell lysis has not been determined. To define the role of NKR-P1A in natural killing, we have generated a mutant of the rat NK cell line, RNK-16, lacking expression of all members of the NKR-P1 receptor family. Although these NKR-P1-deficient NK cells were able to kill many standard tumor targets, including YAC-1, they were selectively deficient in the lysis of IC-21 macrophage, B-16 melanoma, and C1498 lymphoma targets. Reexpression of a single member of the NKR-P1 family, NKR-P1A, on mutant cells restored lysis of IC-21, and killing of IC-21 targets through rat NKR-P1A was completely blocked by F(ab')2 anti-NKR-P1A. Reexpression of NKR-P1A also restored transmembrane signaling to IC-21, as assessed by the generation of inositol-1,4,5-trisphosphate. The generation of inositol-1,4,5-trisphosphate was also restored in response to B-16 targets, but both B-16 and C1498 cells remained resistant to lysis, indicating that other NK cell molecules, perhaps within the NKR-P1 family, are required for the efficient killing of these tumors. These results are the first to demonstrate that NKR-P1A is a target-specific receptor that activates natural killing.
Granzyme A is an interleukin 1 beta-converting enzyme.
Authors: Irmler M , Hertig S , MacDonald H R , Sadoul R , Becherer J D , Proudfoot A , Solari R , Tschopp J
Published: June 2004

Apoptosis is critically dependent on the presence of the ced-3 gene in Caenorhabditis elegans, which encodes a protein homologous to the mammalian interleukin (IL)-1 beta-converting enzyme (ICE). Overexpression of ICE or ced-3 promotes apoptosis. Cytotoxic T lymphocyte-mediated rapid apoptosis is induced by the proteases granzyme A and B. ICE and granzyme B share the rare substrate site of aspartic acid, after which amino acid cleavage of precursor IL-1 beta (pIL-1 beta) occurs. Here we show that granzyme A, but not granzyme B, converts pIL-1 beta to its 17-kD mature form. Major cleavage occurs at Arg120, four amino acids downstream of the authentic processing site, Asp116. IL-1 beta generated by granzyme A is biologically active. When pIL-1 beta processing is monitored in lipopolysaccharide-activated macrophage target cells attacked by cytotoxic T lymphocytes, intracellular conversion precedes lysis. Prior granzyme inactivation blocks this processing. We conclude that the apoptosis-inducing granzyme A and ICE share at least one downstream target substrate, i.e., pIL-1 beta. This suggests that lymphocytes, by means of their own converting enzyme, could initiate a local inflammatory response independent of the presence of ICE.
Circulating allergen-reactive T cells from patients with atopic dermatitis and allergic contact dermatitis express the skin-selective homing receptor, the cutaneous lymphocyte-associated antigen.
Authors: Santamaria Babi L F , Picker L J , Perez Soler M T , Drzimalla K , Flohr P , Blaser K , Hauser C
Published: June 2004

The cutaneous lymphocyte-associated antigen (CLA) is the major T cell ligand for the vascular adhesion molecule E-selectin, and it has been proposed to be involved in the selective targeting of memory T cells reactive with skin-associated Ag to cutaneous inflammatory sites. To further investigate the relation of CLA and cutaneous T cell responses, we analyzed the CLA phenotype of circulating memory T cells in patients with allergic contact dermatitis and atopic dermatitis (AD) alone vs in patients manifesting bronchopulmonary atopy (asthma with or without AD) and nonallergic individuals. Significant T cell proliferative responses to Ni, a contact allergen, and to the house dust mite (HDM), an allergen to which sensitization is often observed in AD and/or asthma, was noted only in allergic and atopic individuals, respectively. When the minor circulating CLA+CD3+CD45RO+ subset was separated from the major CLA-CD3+CD45RO+ subpopulation in Ni-sensitive subjects, the Ni-dependent memory T cell response was largely confined to the CLA+ subset. A similar restriction of the T cell proliferative response to the CLA+ memory subset was observed for HDM in patients with AD alone. In HDM-sensitive patients with asthma with or without AD, however, the CLA- subset exhibited a strong antigen-dependent proliferation, in contrast to patients with AD alone, whose CLA- subset proliferated very weakly to HDM. In asthma with or without AD, the HDM-dependent proliferation slightly predominated in the CLA- when compared to the CLA+ subset. The functional linkage between CLA expression and disease-associated T cell effector function in AD was also demonstrated by the finding that the circulating CLA+ T cell subset in AD patients, but not nonatopic controls, selectively showed both evidence of prior activation (human histocompatibility antigen-DR expression) and spontaneous production of interleukin 4 but not interferon-gamma. Taken together, these observations demonstrate the correlation of CLA expression on circulating memory T cells and disease-associated memory T cell responses in cutaneous hypersensitivity, and they suggest the existence of mechanisms capable of sorting particular T cell Ag specificities and lymphokine patterns into homing receptor-defined memory subsets.
Theiler's virus infection of 129Sv mice that lack the interferon alpha/beta or interferon gamma receptors.
Authors: Fiette L , Aubert C , Müller U , Huang S , Aguet M , Brahic M , Bureau J F
Published: June 2004

The Daniels strain of Theiler's virus causes a persistent infection of the white matter of spinal cord of susceptible mice, with chronic inflammation and primary demyelination. Inbred 129Sv mice are resistant to this infection; they present with mild encephalomyelitis and clear the infection within a matter of days. A very different outcome was observed with inbred 129Sv mice whose receptors for interferon alpha/beta or interferon gamma had been inactivated by homologous recombination. The former presented severe encephalomyelitis with acute infection of neurons, particularly in brain and hippocampus, and extensive infection with necrosis of the choroid plexus. Most animals died of this acute disease. The latter, presented the same early encephalomyelitis as the control 129Sv mice. However, they remained persistently infected and developed a very severe late infection of the white matter with extensive primary demyelination. This late disease looked like an exacerbated form of the chronic demyelinating disease observed in susceptible inbred mice such as the SJL/J or FVB strains. Our results show that the two interferon systems play nonredundant roles in the resistance of the 129Sv mouse to the infection by Theiler's virus. They also lend support to the notion that the Ifg gene is involved in the resistance/susceptibility of inbred strains of mice to persistent infection by this picornavirus.
Chemoattractants induce rapid release of the interleukin 1 type II decoy receptor in human polymorphonuclear cells.
Authors: Colotta F , Orlando S , Fadlon E J , Sozzani S , Matteucci C , Mantovani A
Published: June 2004

Molecules representative of different classes of chemotactic agents, including formyl-Met-Leu-Phe (FMLP), C5a, leukotriene B4, platelet-activating factor, and interleukin (IL)-8, caused a rapid reduction in the IL-1 binding capacity by human polymorphonuclear leukocytes (PMN), a cell type expressing predominantly the IL-1 type II decoy receptor (IL-1 decoy RII). N-t-Boc-Met-Leu-Phe, an antagonist for the FMLP receptor, inhibited the loss of IL-1 binding capacity induced by FMLP. Monocyte chemotactic protein 1, a chemokine related to IL-8 but inactive on PMN, had no effect on IL-1 binding in this cell type. FMLP was selected for further detailed analysis of chemoattractant-induced loss of IL-1 binding by PMN. The action of FMLP was rapid, reaching 50% of its maximum (80%) at 30 s, the earliest measurable time point, and plateauing between 10 and 30 min. Dose-response analysis revealed that maximal reduction of IL-1 binding was reached at FMLP concentrations that were also optimal for chemotaxis (50% effective dose = 5 x 10(-9) M). The loss of IL-1 binding capacity caused by FMLP was determined by a reduction in receptor number with no change in their affinity. The effect of FMLP on IL-1 receptor (IL-1R) was selective in that the PMN surface structures IL-8R, CD16, CD18, and major histocompatibility complex class I antigens were unaffected under these conditions. Loss of surface IL-1R was not due to an augumented rate of internalization. FMLP caused rapid release of a 45-kD IL-1-binding molecule identified as the IL-1 decoy RII. After FMLP-induced release, PMN reexpressed newly synthesized receptors, reaching basal levels by 4 h. FMLP-induced release of the IL-1 decoy RII did not impair the responsiveness of PMN to IL-1 in terms of promotion of survival and cytokine production. FMLP-induced release of the IL-1 decoy RII was unaffected by protein synthesis inhibitors, was blocked by certain protease inhibitors, and was mimicked by agents (the Ca++ ionophore A23187 and phorbol myristate acetate) that recapitulate elements in the signal transduction pathway of chemoattractant receptors. The time frame and concentration range of chemoattractant-induced rapid release of the IL-1 decoy RII are consistent with the view that IL-1 decoy RII release is an early event in the multistep process of leukocyte recruitment.(ABSTRACT TRUNCATED AT 400 WORDS)
Cloning, mapping, and characterization of activated leukocyte-cell adhesion molecule (ALCAM), a CD6 ligand.
Authors: Bowen M A , Patel D D , Li X , Modrell B , Malacko A R , Wang W C , Marquardt H , Neubauer M , Pesando J M , Francke U
Published: June 2004

Antibody-blocking studies have demonstrated the role of CD6 in thymocyte-thymic epithelial (TE) cell adhesion. Here we report that CD6 expressed by COS cells mediates adhesion to TE cells and that this interaction is specifically blocked with an anti-CD6 monoclonal antibody (mAb) or with a mAb (J4-81) that recognized a TE cell antigen. We isolated and expressed a cDNA clone encoding this antigen and show that COS cells transfected with this cDNA bind a CD6 immunoglobulin fusion protein (CD6-Rg). This antigen, which we named ALCAM (activated leukocyte-cell adhesion molecule) because of its expression on activated leukocytes, appears to be the human homologue of the chicken neural adhesion molecule BEN/SC-1/DM-GRASP. The gene was mapped to human chromosome 3q13.1-q13.2 by fluorescence in situ hybridization of cDNA probes to metaphase chromosomes. We prepared an ALCAM-Rg fusion protein and showed that it binds to COS cell transfectants expressing CD6, demonstrating that ALCAM is a CD6 ligand. The observations that ALCAM is also expressed by activated leukocytes and that both ALCAM and CD6 are expressed in the brain suggest that ALCAM-CD6 interactions may play a role in the binding of T and B cells to activated leukocytes, as well as in interactions between cells of the nervous system.
Class I major histocompatibility complex-restricted cytotoxic T lymphocytes specific for Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines against which they were raised.
Authors: Hill A B , Lee S P , Haurum J S , Murray N , Yao Q Y , Rowe M , Signoret N , Rickinson A B , McMichael A J
Published: June 2004

We have raised CD8+ cytotoxic T lymphocytes (CTL) from three Epstein-Barr virus-seropositive donors by incubating peripheral blood lymphocytes with irradiated autologous B95.8-strain EBV-transformed B lymphoblastoid cells (LCL). However, to detect lysis in a standard 51Cr release assay of the LCL against which these CTL were raised, superinfection with recombinant vaccinia expressing the appropriate EBV protein or incubation with the peptide epitope was necessary. The untreated LCL were not lysed, even though Western blotting demonstrated that they expressed the EBV antigens containing the CTL epitopes. We have found CTL of this phenotype that are restricted by human leukocyte antigen-A2, -A3, -B7, or -B39, and which recognize the EBV latent proteins, EBV nuclear antigen (EBNA)-3A, EBNA-3C, or terminal protein. During these experiments, we identified a new human leukocyte antigen-A3-restricted EBNA-3A epitope, residues 603-611, RLRAEAGVK. We raised a spontaneous LCL, transformed by endogenous EBV, from one donor, but this was also not lysed. For at least one of the epitopes, CTL from another donor lysed the LCL without superinfection or addition of peptides. We conclude that the CTL were unable to achieve a high enough avidity of interaction with untreated LCL to trigger effector function, although the LCL were able to stimulate them to grow in vitro for up to 4 mo. To assess whether a small percentage of the LCL might possess a higher antigen density, we used an assay of tumor necrosis factor release from a CTL clone, which was able to detect antigen-bearing cells representing only 1% of a stimulating LCL population. Nevertheless, the untreated autologous LCL line failed to stimulate tumor necrosis factor release.
HIVgp120 activates autoreactive CD4-specific T cell responses by unveiling of hidden CD4 peptides during processing.
Authors: Salemi S , Caporossi A P , Boffa L , Longobardi M G , Barnaba V
Published: June 2004

T cells are made tolerant only to those self-peptides that are presented in sufficient amounts by antigen-presenting cells. They ignore cryptic self-determinants, such as either those not generated by processing machinery or generated in insufficient amounts. It is anticipated that mechanisms that either change antigen processing or increase the yield of previously "invisible" peptides may be capable of inducing T cell priming and, if they are self-maintained, may sustain autoimmune diseases. Herein, we demonstrate for the first time a mechanism by which the gp120 human immunodeficiency virus-I, by downregulating plasma membrane CD4 and increasing its processing, unveils hidden CD4 epitopes, inducing an autoimmune-specific T cell response.
Prevention of age-related T cell apoptosis defect in CD2-fas-transgenic mice.
Authors: Zhou T , Edwards C K , Mountz J D
Published: June 2004

T cell dysfunction and thymic involution are major immunologic abnormalities associated with aging. Fas (CD95) is a bifunctional molecule that is critical for apoptosis and stimulation during T cell development, but the role of Fas during aging has not been determined. Fas expression and function on T cells from old (22-26-mo-old) mice was compared with young (2-mo-old) mice and old CD2-fas-transgenic mice. Fas expression and ligand-induced apoptosis were decreased on T cells from old mice compared with young mice. This correlated with an age-related increase in CD44+Fas- T cells. There was a marked decrease in the proliferation of T cells from old mice after anti-CD3 stimulation compared with young mice. Anti-CD3-stimulated T cells from young mice exhibited increased production of interleukin (IL)-2 and decreased production of interferon-gamma and IL-10 compared with old mice. There was an age-related decrease in the total thymocyte count from 127 +/- 10 cells in young mice compared with 26 +/- 8 x 10(6) in old mice. In 26-mo-old CD2-fas-transgenic mice, Fas and CD44 expression, Fas-induced apoptosis, T cell proliferation, and cytokine production were comparable to that of the young mice. These results suggest that T cell senescence with age is associated with defective apoptosis, and that the CD2-fas transgene allows maintenance of Fas apoptosis function and T cell function in aged mice comparable to that of young mice.
Antigen capture and major histocompatibility class II compartments of freshly isolated and cultured human blood dendritic cells.
Authors: Nijman H W , Kleijmeer M J , Ossevoort M A , Oorschot V M , Vierboom M P , van de Keur M , Kenemans P , Kast W M , Geuze H J , Melief C J
Published: June 2004

Dendritic cells (DC) represent potent antigen-presenting cells for the induction of T cell-dependent immune responses. Previous work on antigen uptake and presentation by human DC is based largely on studies of blood DC that have been cultured for various periods of time before analysis. These cultured cells may therefore have undergone a maturation process from precursors that have different capacities for antigen capture and presentation. We have now used immunoelectron microscopy and antigen presentation assays to compare freshly isolated DC (f-DC) and cultured DC (c-DC). f-DC display a round appearance, whereas c-DC display characteristic long processes. c-DC express much more cell surface major histocompatibility complex (MHC) class II than f-DC. The uptake of colloidal gold-labeled bovine serum albumin (BSA), however, is greater in f-DC, as is the presentation of 65-kD heat shock protein to T cell clones. The most striking discovery is that the majority of MHC class II molecules in both f-DC and c-DC occur in intracellular vacuoles with a complex shape (multivesicular and multilaminar). These MHC class II enriched compartments (MIIC) represent the site to which BSA is transported within 30 min. Although MIIC appear as more dense structures with less MHC class II molecules in f-DC than c-DC, the marker characteristics are very similar. The MIIC in both types of DC are acidic, contain invariant chain, and express the recently described HLA-DM molecule that can contribute to antigen presentation. CD19+ peripheral blood B cells have fewer MIIC and surface MHC class II expression than DCs, while monocytes had low levels of MIIC and surface MHC class II. These results demonstrate in dendritic cells the elaborate development of MIIC expressing several of the components that are required for efficient antigen presentation.
N-formylpeptide and complement C5a receptors are expressed in liver cells and mediate hepatic acute phase gene regulation.
Authors: McCoy R , Haviland D L , Molmenti E P , Ziambaras T , Wetsel R A , Perlmutter D H
Published: June 2004

Although the classical chemotactic receptor for complement anaphylatoxin C5a has been associated with polymorphonuclear and mononuclear phagocytes, several recent studies have indicated that this receptor is expressed on nonmyeloid cells including human endothelial cells, vascular smooth muscle cells, bronchial and alveolar epithelial cells, hepatocytes, and in the human hepatoma cell line HepG2. In this study, we examined the possibility that other members of the chemotactic receptor family are expressed in HepG2 cells and human liver, and the possibility that such receptors mediate changes in acute phase gene expression in HepG2 cells. Using polymerase chain reaction (PCR) amplification of HepG2 mRNA with primers based on highly conserved regions of the chemotactic subgroup of the G protein-coupled receptor family, we identified a PCR fragment from the formyl-methionyl-leucyl-phenylalanine (FMLP) receptor, as well as one from the C5a receptor. Immunostaining with antipeptide antisera to FMLPR confirmed the presence of this receptor in HepG2 cells. Receptor binding studies showed specific saturable binding of a radioiodinated FMLP analogue to HepG2 cells (Kd approximately 2.47 nM; R approximately 6 x 10(3) plasma membrane receptors per cell). In situ hybridization analysis showed the presence of FMLPR mRNA in parenchymal cells of the human liver in vivo. Both C5a and FMLP mediated concentration- and time-dependent changes in synthesis of acute phase proteins in HepG2 cells including increases in complement C3, factor B, and alpha 1-antichymotrypsin, as well as concomitant decreases in albumin and transferrin synthesis. The effects of C5a and FMLP on the synthesis of these acute phase proteins was evident at concentrations as low as 1 nM, and they were specifically blocked by antipeptide antisera for the corresponding receptor. In contrast to the effect of other mediators of hepatic acute phase gene regulation, such as interleukin 6, the effects of C5a and FMLP were reversed by increased concentrations well above the saturation point of the respective receptor. These results suggest that acute phase gene regulation by C5a and FMLP is desensitized at high concentrations, a property that is unique among the several known mechanisms for hepatic acute phase gene regulation.
Interleukin 6 is essential for in vivo development of B lineage neoplasms.
Authors: Hilbert D M , Kopf M , Mock B A , Köhler G , Rudikoff S
Published: June 2004

Interleukin (IL) 6 has been suggested to be the major cytokine responsible for proliferation of neoplastic plasma cells in both human myeloma and mouse plasmacytoma. Much of the evidence supporting this suggestion is derived from in vitro studies in which the survival or proliferation of some plasma cell tumors has been found to be IL-6 dependent. However, it remains unclear whether this dependency is the consequence of in vivo or in vitro selective pressures that preferentially expand IL-6-responsive tumor cells, or whether it reflects a critical in vivo role for IL-6 in plasma cell neoplasia. To address this question, we have attempted to induce plasma cell tumors in normal mice and in IL-6-deficient mice generated by introduction of a germline-encoded null mutation in the IL-6 gene. The results demonstrate that mice homozygous (+/+) or heterozygous (+/-) for the wild-type IL-6 allele yield the expected incidences of plasma cell tumors. In contrast, mice homozygous for the IL-6-null allele (-/-) are completely resistant to plasma cell tumor development. These studies define the essential role of IL-6 in the development of B lineage tumors in vivo and provide experimental support for continued efforts to modulate this cytokine in the treatment of appropriate human B cell malignancies.
T cell priming versus T cell tolerance induced by synthetic peptides.
Authors: Aichele P , Brduscha-Riem K , Zinkernagel R M , Hengartner H , Pircher H
Published: June 2004

It is well known that synthetic peptides are able to both induce and tolerize T cells. We have examined the parameters leading either to priming or tolerance of CD8+ cytotoxic T lymphocytes (CTL) in vivo with a major histocompatibility complex class I (H-2 Db) binding peptide derived from the glycoprotein (GP aa33-41) of lymphocytic choriomeningitis virus (LCMV). By varying dose, route, and frequency of LCMV GP peptide application, we found that a single local subcutaneous injection of 50-500 micrograms peptide emulsified in incomplete Freund's adjuvant protected mice against LCMV infection, whereas repetitive and systemic intraperitoneal application of the same dose caused tolerance of LCMV-specific CTL. The peptide-induced tolerance was transient in euthymic mice but permanent in thymectomized mice. These findings are relevant for a selective use of peptides as a therapeutic approach: peptide-induced priming of T cells for vaccination and peptide-mediated T cell tolerance for intervention in immunopathologies and autoimmune diseases.
Expression of functional CD40 by vascular endothelial cells.
Authors: Hollenbaugh D , Mischel-Petty N , Edwards C P , Simon J C , Denfeld R W , Kiener P A , Aruffo A
Published: June 2004

The interaction between activated vascular endothelium and T cells has been shown to play an important role in the recruitment and activation of T cells at sites of inflammation. Here we report the expression of CD40 by vascular endothelial cells and its regulation by inflammatory agents. Using the soluble recombinant CD40 ligand, sgp39, we show that the interaction of CD40 with its ligand can lead to endothelial cell activation, which in turn leads to leukocyte adhesion. This adhesion is partly mediated by the expression of E-selectin. In addition to E-selectin expression, sgp39 induces the expression of intercellular adhesion molecule 1 and augments the tumor necrosis factor alpha-induced expression of vascular cell adhesion molecule 1. The effects of sgp39 on endothelial cells can be blocked with anti-gp39 monoclonal antibody (mAb), anti-CD40 mAb, or soluble CD40. Staining of tissues from healthy human skin using anti-CD40 mAb showed very weak expression of CD40 by the endothelium, while skin involved in inflammatory disease showed marked upregulation of CD40 expression. These studies suggest that interactions between cell surface proteins expressed by activated T cells with their receptors on vascular endothelium can stimulate the vasculature at sites of inflammation and may be involved in normal inflammatory responses and in inflammatory disease.
Activation of CD4+ T cells in the presence of a nondepleting monoclonal antibody to CD4 induces a Th2-type response in vitro.
Authors: Stumbles P , Mason D
Published: June 2004

In vitro experiments using purified rat CD4+ T cells in primary and secondary mixed leukocyte cultures (MLC) have been carried out to explore the mechanism of inhibition of cell-mediated autoimmune disease in the rat by a nondepleting monoclonal antibody (mAb) to CD4. Previous work has shown that W3/25, a mouse anti-rat CD4 mAb of immunoglobulin G1 isotype, completely prevents the development of the paralysis associated with experimental allergic encephalomyelitis (EAE) in Lewis rats, but does so without eliminating the encephalitogenic T cells. The in vitro experiments described in this study have shown that when CD4+ T cells were activated in the presence of the anti-CD4 mAb in a primary MLC, the synthesis of interferon (IFN) gamma, but not interleukin (IL) 2, was completely inhibited. After secondary stimulation, now in the absence of the mAb, the synthesis of IL-4 and IL-13 mRNA was greatly enhanced compared with that observed from CD4+ T cells derived from primary cultures in which the mAb was omitted. As IL-4 and IL-13 are known to antagonize cell-mediated immune reactions, and as EAE is cell-mediated disease, the data suggest that the W3/25 mAb controls EAE by modifying the cytokine repertoire of T cells that respond to the encephalitogen. The capacity for the mAb to suppress IFN-gamma synthesis provides, in part, an explanation for this change in cytokine production. These findings are discussed in terms of what is known of the factors that determine which cytokine genes are expressed on T cell activation. Possible implications for the evolution of T cell responses in human immunodeficiency virus infection are also discussed.
CD4+ beta islet cell-reactive T cell clones that suppress autoimmune diabetes in nonobese diabetic mice.
Authors: Akhtar I , Gold J P , Pan L Y , Ferrara J L , Yang X D , Kim J I , Tan K N
Published: June 2004

We report the isolation of a panel of CD4+ T helper type 1 autoreactive T cell clones from the spleen of unprimed nonobese diabetic mice, a murine model of human insulin-dependent diabetes mellitus. The T cell clones express a diverse repertoire of T cell receptors, three of which recognize beta islet cell autoantigen(s). The islet cell-reactive T cell clones inhibit adoptive transfer of insulin-dependent diabetes mellitus and intraislet lymphocytic infiltration. The protective capacity of the T cell clones correlates with their ability to produce a novel immunoregulatory activity that potently inhibits in vitro allogeneic mixed lymphocyte reaction. The partially purified activity significantly inhibited the adoptive transfer of diabetes. Our work provides evidence in support of the existence of T helper type 1, CD4+ T cells reactive to beta islet cell autoantigens that have acquired a protective instead of a diabetogenic effector function. These T cells mediate their protective action in part by production of an immunoregulatory activity capable of down-regulating immune responses, and they are likely to represent a population of regulatory T cells that normally plays a role in maintaining peripheral tolerance.