bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antigen receptor signalling in apoptosis‐resistant mutants of WEHI 231 cells
Authors: Tasker L. , Marshall‐clarke S. 
Published: March 2003

SummaryLigation of membrane immunoglobulin M (mIgM) induces cell cycle arrest and apoptosis in the WEHI 231 B‐lymphoma cell line. The molecular mechanisms which link receptor ligation and the nuclear events that underlie this response, have yet to be fully elucidated. Here we have examined the signals induced following mIgM cross‐linking in variants of WEHI 231 that no longer undergo apoptosis in response to this stimulus. Tyrosine phosphorylation of cellular substrates in two of the variants is identical to that seen in wild‐type cells but in one of the mutants, VS2.12, a restricted set of substrates becomes tyrosine phosphorylated. In a second variant (E8), mIgM cross‐linking does not induce elevation of intracellular Ca2+, although tyrosine phosphorylation of PLCγ2 is induced to an equivalent extent to that seen in WEHI 231 cells. A third variant, 2E10.F9, is resistant to apoptosis despite the fact that all signals analysed appear to be similar to those induced in wild‐type cells. Our findings show that resistance to apoptosis can arise as a result of mutations affecting discrete stages of the mIgM signalling pathway. The mutant lines reported here show defects that have not yet been identified in previous studies and are likely to be useful tools in dissecting the signalling of cell death in B lymphocytes.
Individual and combined effect of granulocyte–macrophage colony‐stimulating factor and prolactin on maturation of dendritic cells from blood monocytes under serum‐free conditions
Authors: Matera L. , Galetto A. , Geuna M. , Vekemans K. , Ricotti E. , Contarini M. , Moro F. , Basso G. 
Published: March 2003

SummaryProlactin (PRL) shares structural and functional features with haemopoietic factors and cytokine peptides. Dendritic cells (DC) are involved in both initiating the primary and boosting the secondary host immune response and can be differentiated in vitro from precursors under the effect of granulocyte–macrophage colony‐stimulating factor (GM‐CSF) plus other factors. Because PRL has been shown to functionally interact with GM‐CSF, we have addressed its role on GM‐CSF‐driven differentiation of DC. Monocytic DC precursors from peripheral blood mononuclear cells (PBMC) were enriched either by adhesion to a plastic surface or CD14‐positive selection and cultured for 7 days in serum‐free medium containing GM‐CSF, interleukin (IL)‐4 and PRL, alone or in combination. Cells with large, veiled cytoplasm, expressing major histocompatibility complex (MHC) class II and the costimulatory molecules CD80, CD86 and CD40 and lacking the monocyte marker CD14, were considered as having the phenotype of cytokine‐generated DC. Functional maturation was assessed by proliferation and interferon‐γ (IFN‐γ) release of allogeneic T lymphocytes. Physiological (10–20 ng/ml) concentrations of PRL interacted synergistically with GM‐CSF and the effect was similar to that induced by IL‐4 on GM‐CSF‐driven DC maturation. When used alone, the physiological concentrations of PRL were inhibitory, whereas higher concentrations (80 ng/ml) were stimulatory. The synergistic effect of PRL may in part be caused by its ability to counteract the down‐modulation of the GM‐CSF receptor observed in serum‐free conditions. These data provide further evidence of the significance of PRL in the process of T lymphocyte activation.
Differential cellular immunolocalization of renal tumour necrosis factor‐α production during ischaemia versus endotoxaemia
Authors: Donnahoo K. K. , Meng X. , Ao L. , Ayala A. , Shames B. D. , Cain M. P. , Harken A. H. , Meldrum D. R. 
Published: March 2003

SummaryBoth renal ischaemia and endotoxaemia provoke renal dysfunction and cellular injury. Although the clinical manifestation of each insult is similar (global renal dysfunction), ischaemia and endotoxaemia induce different patterns of cellular injury. Tumour necrosis factor‐α (TNF‐α) has been implicated in both types of renal injury; however, it remains unknown whether differential cellular TNF‐α expression accounts for these changes. We hypothesized that renal glomerular cells and tubular cells differentially express TNF‐α in response to ischaemia compared with endotoxaemia. To investigate this hypothesis, male Sprague–Dawley rats were anaesthetized and exposed to various time‐periods of renal ischaemia, with or without reperfusion (sham operation=negative control), or lipopolysaccharide (LPS) 0·5 mg/kg intraperitoneally (i.p.). The kidneys were harvested following renal injury, and rat TNF‐α protein expression was determined (by enzyme‐linked immunosorbent assay), as were TNF‐α bioactivity (by WEHI‐164 cell clone cytotoxicity assay) and TNF‐α cellular localization (by immunohistochemistry). TNF‐α protein expression and TNF‐α bioactivity peaked following 1 hr of ischaemia and 2 hr of reperfusion (48 ± 11 pg/mg of protein, P < 0·05, and 12 ± 0·5 × 10−3 units/mg of protein, P < 0·05, respectively). The concentration of TNF‐α increased to a similar extent following exposure to LPS; however, while TNF‐α production following ischaemia‐reperfusion injury localized predominantly to renal tubular epithelial cells, animals exposed to LPS demonstrated a primarily glomerular distribution of TNF‐α production. Hence, the cellular localization of renal TNF‐α production appears to be injury specific, i.e. renal tubular cells are the primary source of TNF‐α following an ischaemic insult, whereas LPS induces glomerular TNF‐α production. The cellular source of TNF‐α following different insults may have therapeutic implications for targeted inhibition of TNF‐α production.
Low concentrations of lipopolysaccharide synergize with peptides to augment human T‐cell proliferation and can prevent the induction of non‐responsiveness by CTLA4‐Ig
Authors: Goodier M. R. , Londei M. 
Published: March 2003

SummaryWe investigate how lipopolysaccharide (LPS) could influence antigen‐specific T‐cell responses as well as tolerance induction. Using the recall antigen tetanus toxoid for primary in vitro T‐cell stimulation, we observed that LPS synergized with peptides to augment proliferation, particularly when used at low concentrations (as little as 100 pg/ml), and that interleukin‐12 (IL‐12) was partially required for this synergistic effect. Because of the clear enhancement of in vitro peptide‐specific responses we then tested whether LPS could influence antigen‐specific tolerance driven by coincubation of antigen (tetanus toxoid; TT or immunodominant peptides) with human CTLA‐4Ig fusion protein. As expected, CTLA‐4Ig treatment inhibited responses to peptides. LPS (100 pg/ml) induced a partial recovery of primary in vitro proliferation under these conditions and the presence of LPS during the primary stimulation prevented the induction of tolerance normally observed on re‐stimulation with the same antigen alone. Contrary to the synergistic effects on peptide proliferation this action was not caused by release of IL‐12. In addition, the neutralization of tumour necrosis factor‐α (TNF‐α) during the primary stimulation did not inhibit proliferation on re‐stimulation with peptide. LPS could therefore exert dramatic effects on antigen‐specific proliferation and CTLA‐4Ig‐induced non‐responsiveness in human T cells, although via distinct mechanisms. These results reinforce the evidence that LPS influences T‐cell function, most likely as a consequence of myeloid cell activation.
Effect of early fetal splenectomy on prenatal B‐cell development in sheep
Authors: Press C. McL. , McCullagh P. , Landsverk T. 
Published: March 2003

SummaryThe contribution of early splenic B‐cell populations to the colonization of the ileal Peyer's patch was investigated following the surgical removal of the spleen in a series of 56‐day‐old fetal sheep. The fetuses were killed at 140 days of gestation and the ileal Peyer's patch, the distal jejunal lymph node which drains the Peyer's patch, and a peripheral lymph node, the superficial cervical lymph node, were examined. Enzyme and immunohistochemical evaluation concluded that the distribution of B cells, T cells and stromal cells in the ileal Peyer's patch was similar in splenectomized and normal fetal sheep. Thus, the presence of the fetal spleen was not essential for the colonization of the ileal Peyer's patch and other early sites of B‐cell accumulation would appear capable of generating the necessary precursor populations. Investigation of B‐cell populations in lymph nodes used a combination of terminal deoxynucleotidyl‐transferase‐mediated deoxyuridine‐triphosphate nick‐end‐labelling (TUNEL) histochemistry and immunofluorescence to determine the average number of apoptotic B cells in the primary follicles of the outer cortex of splenectomized and normal lambs. A significantly increased number of apoptotic B cells was present in the distal jejunal lymph node but not in the superficial cervical lymph node of splenectomized lambs. This finding suggests that splenectomy affected prenatal B‐cell development in fetal sheep and raises questions as to the regulation of B‐cell lymphopoiesis in a species using a post‐rearrangement organ of diversification.
The failure of Daudi cells to express the cellular prion protein is caused by a lack of glycosyl‐phosphatidylinositol anchor formation
Authors: Morelon E. , Dodelet V. , Lavery P. , Cashman N. R. , Loertscher R 
Published: March 2003

SummaryThe cellular prion protein (PrPc) is a glycosyl‐phosphatidylinositol (GPI)‐linked cell surface protein, which is expressed at high density on nervous tissues and at lower levels on most other solid‐organ tissues. It is also expressed on peripheral blood mononuclear cells (PBMC) of all lineages. In lymphocytes, its level of expression is dependent upon the state of cell activation, and polyclonal anti‐PrP antisera partially block lectin‐induced T‐cell activation, suggesting a functional role of the protein in this process. Using the monoclonal antibody (mAb) 3F4 we examined PrPc surface immunoreactivity on leukaemic cell lines of T‐ and B‐cell origin, and unexpectedly observed a complete lack of PrPc cell‐surface expression in Daudi cells, while all other cell lines displayed discernible reactivity. We demonstrated the intracellular presence of PrP‐specific mRNA and PrP protein. The lack of surface PrPc is unrelated to the well‐known defect of β2‐microglobulin (β2m) expression in Daudi cells as other β2m‐deficient cells, such as the melanoma cell line F0‐1 and spleen cells from β2m gene‐deleted mice, were not deficient in cell‐surface PrPc. Daudi cells failed to bind antibodies directed against all GPI‐linked cell surface proteins. In somatic hybridization experiments using murine spleen cells as partners, we observed de novo expression of human PrPc, CD55 and CD59, thus demonstrating in Daudi cells the availability of these gene products for GPI linkage and cell‐surface expression.
Immunological memory in B‐cell‐deficient mice conveys long‐lasting protection against genital tract infection with Chlamydia trachomatis by rapid recruitment of T cells
Authors: Johansson M. , Lycke N. 
Published: March 2003

SummaryThe role of antibodies and antigen deposition for the development of immunological memory has been incompletely investigated. We addressed whether long‐term protection and T‐cell memory can be stimulated against a genital tract infection with human Chlamydia trachomatis serovar D in B‐cell‐deficient (µMT) mice. At 6 months following a primary infection with C. trachomatis, both µMT and wild‐type (WT) mice exhibited strong and comparable protection against reinfection. Evidence of long‐lasting CD4+ T‐cell memory was found in both µMT and WT mice, typified by comparable delayed‐type hypersensitivity (DTH) reactions against chlamydial antigens. No bacterial or chlamydial DNA was found in the genital tract of µMT memory mice, suggesting that immunological memory was maintained in the absence of antigen. Whereas few T cells were present in the genital tract of memory mice, rapid recruitment of CD4+, and some CD8+, T cells into the genital tract tissue was observed after challenge with live bacteria. Accumulation of T cells in the genital tract was preceded by a short transient infection of similar magnitude in both µMT and WT memory mice, arguing against a long‐term protective role of local antibodies. The rapid recruitment of CD4+ T cells into the genital tract was associated with a transient detection of interferon‐γ (IFN‐γ) mRNA in the genital tract in chlamydia‐immune memory mice, which was not found in naïve, challenged mice. Thus, long‐term protection in the genital tract against C. trachomatis infection is conveyed by IFN‐γ‐producing CD4+ memory T cells, which appear to be maintained in the absence of antibodies and local antigen deposition.
Interleukin‐10 induces macrophage apoptosis and expression of CD16 (FcγRIII) whose engagement blocks the cell death programme and facilitates differentiation
Authors: Wang Z.‐Q. , Bapat A. S. , Rayanade R. J. , Dagtas A. S. , Hoffmann M. K. 
Published: March 2003

SummaryThe development of monocytes into macrophages is regulated by helper T cells (Th) cells and, vice versa, the differentiation of Th cells into Th1 and Th2 is regulated by macrophages. Herein we examined the role of the Th2 cytokine, interleukin‐10 (IL‐10), on the development of macrophages. IL‐10 is known to block the expression of antigen‐presenting major histocompatibility complex (MHC) II and of costimulatory B7 molecules but it induces the expression of FcRs, especially the FcγRIII (CD16). The expression of CD16 enables the macrophage to carry out antibody‐dependent cell‐mediated cytotoxicity (ADCC) functions. However, this differentiation step is largely undercut by the capacity of IL‐10 to induce macrophage apoptosis before the process of differentiation ensues. We found that the negative effect of IL‐10 on the survival of macrophages is reversed in an environment that contains immunoglobulin G (IgG). IgG, especially when immune complexed with antigen, stimulates CD16 to transmit survival signals in macrophages which enable them to complete the differentiation process into CD16+ cells. Thus, IL‐10 suppresses macrophage accumulation in healthy tissues where IgG is absent, and facilitates macrophage accumulation and differentiation in tissues that contain IgG, for example inflamed tissues or tissues that present autoreactive antibodies.
Nitric oxide and bone
Authors: Van'T Hof Rob J. , Ralston Stuart H. 
Published: March 2003

SummaryNitric oxide (NO) is a free radical which has important effects on bone cell function. The endothelial isoform of nitric oxide synthase (eNOS) is widely expressed in bone on a constitutive basis, whereas inducible NOS is only expressed in response to inflammatory stimuli. It is currently unclear whether neuronal NOS is expressed by bone cells. Pro‐inflammatory cytokines such as IL‐1 and TNF cause activation of the iNOS pathway in bone cells and NO derived from this pathway potentiates cytokine and inflammation induced bone loss. These actions of NO are relevant to the pathogenesis of osteoporosis in inflammatory diseases such as rheumatoid arthritis, which are characterized by increased NO production and cytokine activation. Interferon gamma is a particularly potent stimulator of NO production when combined with other cytokines, causing very high concentrations of NO to be produced. These high levels of NO inhibit bone resorption and formation and may act to suppress bone turnover in severe inflammation. The eNOS isoform seems to play a key role in regulating osteoblast activity and bone formation since eNOS knockout mice have osteoporosis due to defective bone formation. Other studies have indicated that the NO derived from the eNOS pathway acts as a mediator of the effects of oestrogen in bone. eNOS also mediates the effects of mechanical loading on the skeleton where it acts along with prostaglandins, to promote bone formation and suppress bone resorption. Pharmacological NO donors have been shown to increase bone mass in experimental animals and preliminary evidence suggests that these agents may also influence bone turnover in man. These data indicate that the l‐arginine/NO pathway represents a novel target for therapeutic intervention in the prevention and treatment of bone diseases.
Disrupted B‐lymphocyte development and survival in interleukin‐2‐deficient mice
Authors: Schultz Michael , Clarke Stephen H. , Arnold Larry W. , Sartor R. Balfour , Tonkonogy Susan L. 
Published: March 2003

SummaryInterleukin‐2‐deficient (IL‐2−/−) mice develop a spontaneous, progressive, CD4+ T‐cell‐mediated colitis with an age‐related decrease in the number of B lymphocytes. The aim of this study was to determine the mechanisms of B‐cell loss in IL‐2−/− mice. Serum immunoglobulin G1 (IgG1) levels in 8‐week‐old IL‐2−/− mice were above normal but then decreased dramatically with advancing age. Between 8 and 11 weeks of age, the number of B‐cell progenitors (B220+ IgM−) in the bone marrow of IL‐2−/− mice was less than half of those in IL‐2+/+ littermates. By 22 weeks of age, very few progenitor cells remained in the bone marrow of most mice, and spleens were almost devoid of B cells. Likewise, B1 cells were not present in the peritoneal cavity of aged IL‐2−/− mice. Flow cytometry analysis of B‐cell differentiation in the bone marrow suggested a progressive loss of B cells from the most mature to the least mature stages, which was not dependent on IL‐2 receptor‐α (IL‐2Rα) expression. B cells transferred from normal animals had similar survival rates in IL‐2−/− and wild‐type mice. We conclude that conventional B cells in older IL‐2−/− mice are lost by attrition owing to a derangement in B‐cell development. Because B1 cells are less dependent on the bone marrow, a separate mechanism for their loss is suggested.
Differential modulation of CD8β by rat γδ and αβ T cells after activation
Authors: Straube Frank , Herrmann Thomas 
Published: March 2003

SummaryMajor histocompatibility complex (MHC) class I‐restricted αβ T cells express the CD8αβ heterodimer, which acts as a MHC class I‐specific co‐receptor. Rats are so far the only species with frequent expression of the CD8αβ by MHC‐unrestricted γδ T cells. This study compares CD8αβ expression by splenic rat αβ and γδ T cells and reveals a lineage‐specific difference in the control of CD8β expression. After activation in vitro, many γδ T cells, but not αβ T cells, persistently down‐modulate the expression of CD8β, but not CD8α, at the RNA level. Down‐regulation occurred after stimulation with T‐cell receptor (TCR)‐specific monoclonal antibody (mAb) and interleukin‐2 (IL‐2) or CD28‐mediated costimulation, and after activation with phorbol 12‐myristate 13‐acetate (PMA) and ionomycin. Functional differences between modulating and non‐modulating cells were not found with respect to interferon‐γ (IFN‐γ) production and cytolytic activity. The modulation could be indicative for a fundamental difference between αβ and γδ T cells and also limits the use of CD8β as a stable marker of γδ T‐cell subsets. Possibly, CD8β modulation provides a mechanism to escape over‐stimulation by (auto‐)antigens by increasing the threshold of TCR‐mediated activation in γδ T cells.
Interleukin‐1β, but not interleukin‐1α, is required for T‐cell‐dependent antibody production
Authors: Nakae Susumu , Asano Masahide , Horai Reiko , Iwakura Yoichiro 
Published: March 2003

SummaryInterleukin‐1 (IL‐1) consists of two molecules, IL‐1α and IL‐1β, and IL‐1 receptor antagonist (IL‐1Ra) is a natural inhibitor of these molecules. Although the adjuvant effects of exogenously administered IL‐1 in the humoral immune response are well known, the roles of endogenous IL‐1 and the functional discrimination between IL‐1α and IL‐1β have not been elucidated completely. In this report, we investigated the role of IL‐1 in the humoral immune response using gene‐targeted mice. Both primary and secondary antibody production against T‐dependent antigen, sheep red blood cells (SRBC), was significantly reduced in IL‐1α/β−/− mice, and was enhanced in IL‐1Ra−/− mice. The intrinsic functions of B cells, such as antibody production against type 1 T‐independent antigen, trinitrophenyl–lipopolysaccharide and proliferative responses against mitogenic stimuli, were normal in IL‐1α/β−/− mice. The proliferative response of T cells and cytokine production upon stimulation with anti‐CD3 monoclonal antibody were also normal, as was the phagocytotic ability of antigen‐presenting cells (APCs). However, SRBC‐specific proliferative response and cytokine production of T cells through the interaction with APCs were markedly impaired in IL‐1α/β−/− mice, and enhanced in IL‐1Ra−/− mice. Moreover, we show that SRBC‐specific antibody production was reduced in IL‐1β−/− mice, but not in IL‐1α−/− mice. These results show that endogenous IL‐1β, but not IL‐1α, is involved in T‐cell‐dependent antibody production, and IL‐1 promotes the antigen‐specific T‐cell helper function through the T‐cell–APC interaction.
Interleukin‐10 promotes B16‐melanoma growth by inhibition of macrophage functions and induction of tumour and vascular cell proliferation
Authors: García‐Hernández M. L. , Hernández‐Pando R. , Gariglio P. , Berumen J. 
Published: March 2003

SummaryThe aim of this study was to investigate the mechanisms by which interleukin‐10 (IL‐10) induces tumour growth in a mouse‐melanoma model. A B16‐melanoma cell line (B16‐0) was transfected with IL‐10 cDNA and three clones that secreted high (B16‐10), medium and low amounts of IL‐10 were selected. Cell proliferation and IL‐10 production were compared in vitro, and tumour growth, percentages of necrotic areas, tumour cells positive for proliferating cell nuclear antigen (PCNA), IL‐10 receptor (IL‐10R) and major histocompatibility complex type I (MHC‐I) and II (MHC‐II), as well as infiltration of macrophages, CD4+ and CD8+ lymphocytes and blood vessels were compared in vivo among IL‐10‐transfected and non‐transfected tumours. Proliferation and tumour growth were greater for IL‐10‐transfected than for non‐transfected cells (P < 0·001), and correlated with IL‐10 concentration (r ≥ 0·79, P < 0·006). Percentages of tumour cells positive for PCNA and IL‐10R were 4·4‐ and 16·7‐fold higher, respectively, in B16‐10 than in B16‐0 tumours (P < 0·001). Macrophage distribution changed from a diffuse pattern in non‐transfected (6·4 ± 1·7%) to a peripheral pattern in IL‐10‐transfected (3·8 ± 1·7%) tumours. The percentage of CD4+ lymphocytes was 7·6 times higher in B16‐10 than in B16‐0 tumours (P = 0·002). The expression of MHC‐I molecules was present in all B16‐0 tumour cells and completely negative in B16–10 tumour cells. In B16‐0 tumours, 89 ± 4% of the whole tumour area was necrotic, whereas tumours produced by B16‐10 cells showed only 4·3 ± 6% of necrotic areas. IL‐10‐transfected tumours had 17‐fold more blood vessels than non‐transfected tumours (61·8 ± 8% versus 3·5 ± 1·7% blood vessels/tumour; P < 0·001). All the effects induced by IL‐10 were prevented in mice treated with a neutralizing anti‐IL‐10 monoclonal antibody. These data indicate that IL‐10 could induce tumour growth in this B16‐melanoma model by stimulation of tumour‐cell proliferation, angiogenesis and immunosuppression.