bluuebunny/crossref_metadata_2025 huggingface dataset:
CD1d structure and regulation on human thymocytes, peripheral blood T cells,B cells and monocytes
Authors: Exley M. , Garcia J. , Wilson S. B. , Spada F. , Gerdes D. , Tahir S. M. A. , Patton K. T. , Blumberg¶ R. S. , Porcelli S. , Chott** A. , Balk S. P.
Published: March 2003

Human T cells expressing CD161 and an invariant T‐cell receptor (TCR) α‐chain (Vα24invt T cells) specifically recognize CD1d and appear to have immunoregulatory functions. However, the physiological target cells for this T‐cell population, and whether alterations in CD1d expression contribute to the regulation of Vα24invt T‐cell responses, remain to be determined. A series of antibodies were generated to assess CD1d expression, structure and regulation on human lymphoid and myeloid cells. CD1d was expressed at high levels by human cortical thymocytes and immunoprecipitation analyses showed it to be a 48 000‐MW glycosylated protein. However, after solubilization, the majority of the thymocyte CD1d protein, but not CD1d expressed by transfected cells, lost reactivity with monoclonal antibodies (mAbs) against native CD1d, indicating that it was alternatively processed. Moreover, thymocytes were not recognized by CD1d‐reactive Vα24invt T‐cell clones. Medullary thymocytes and resting peripheral blood T cells were CD1d–, but low‐level CD1d expression was induced on activated T cells. CD1d was expressed by B cells in peripheral blood and lymph node mantle zones, but germinal centres were CD1d–. Resting monocytes were CD1d+ but, in contrast to CD1a, b and c, their surface expression of CD1d was not up‐regulated by granulocyte–macrophage colony‐stimulating factor (GM‐CSF) and interleukin‐4 (IL‐4) activation. These results demonstrate constitutive CD1d expression by human professional antigen‐presenting cells and that post‐translational processing of CD1d may contribute to regulation of the activity of CD1d‐specific T cells.
The role of complement in the acquired immune response
Authors: Nielsen C. H. , Fischer E. M. , Leslie R. G. Q.
Published: March 2003

Studies over the past three decades have clearly established a central role for complement in the promotion of a humoral immune response. The primary function of complement, in this regard, is to opsonize antigen or immune complexes for uptake by complement receptor type 2 (CR2, CD21) expressed on B cells, follicular dendritic cells (FDC) and some T cells. A variety of mechanisms appear to be involved in complement‐mediated promotion of the humoral response. These include: enhancement of antigen (Ag) uptake and processing by both Ag‐specific and non‐specific B cells for presentation to specific T cells; the activation of a CD21/CD19 complex‐mediated signalling pathway in B cells, which provides a stimulus synergistic to that induced by antigen interaction with the B‐cell receptor (BCR); and promotion of the interaction between B cells and FDC, where C3d‐bearing immune complexes participate in intercellular bridging. Finally, current studies suggest that CR2 may also play a role in the determination of B‐cell tolerance towards self‐antigens and thereby hold the key to the previously observed correlation between deficiencies of the early complement components and autoimmune disease.
Evidence for a unique expression of CD4 on murine vaginal CD4+ cells
Authors: Wormley Jr F. L. , Scott M. , Luo W. , Baker M. , Chaiban J. , Fidel Jr P. L.
Published: March 2003

Mucosal cell‐mediated immunity (CMI) by CD4+ T cells is postulated to be important for host defence against several vaginal pathogens. In addition to the recognized phenotypic distinctions of resident vaginal T lymphocytes, we recently provided evidence by fluorescence‐activated cell sorter (FACS) that murine vaginal CD4+ T lymphocytes, are differentially recognized by two epitope‐distinct anti‐CD4 antibodies, suggesting that the CD4 protein on vaginal CD4+ cells is atypically expressed. In the present study, we confirm this by FACS and immunohistochemistry under non‐denaturing conditions using two additional anti‐CD4 antibodies. However, positive immunohistochemical staining of vaginal CD4+ cells under denaturing conditions revealed that the CD4 epitope in question is indeed present within the CD4 protein. Using reverse transcription polymerase chain reaction, amplification of CD3, T‐cell receptor‐β (TCR‐β), and TCR‐δ mRNA from lymph node and vaginal tissue, and CD4 mRNA from lymph node tissue was demonstrable. In contrast, amplification of CD4 mRNA from vaginal tissue, vaginal enriched lymphoid cells, or a purified (FACS‐sorted) population of vaginal‐specific CD4+ cells using two distinct primer sets was not demonstrable. Altogether, our results provide evidence that the CD4 protein on vaginal CD4+ T cells is conformationally distinct compared with its systemic counterpart, either as a result of a unique CD4 mRNA sequence or from a stable interaction of soluble CD4 with the surface of vaginal T cells.
Adrenaline inhibits macrophage nitric oxide production through β1 and β2 adrenergic receptors
Authors: Sigola L. B. , Zinyama & R. B.
Published: March 2003

This study was conducted to investigate the role of the acute stress hormone adrenaline on macrophage nitric oxide (NO) production. Murine peritoneal macrophages were stimulated in vitro with lipopolysaccharide (LPS) in the absence or presence of adrenaline. Adrenaline inhibited the LPS‐induced nitrite response in a dose‐dependent manner. The suppressive effect of adrenaline on NO production was mediated via β1 and β2 adrenergic receptors since isoprenaline (a non‐selective β1 and β2 agonist), dobutamine and salbutamol (selective β1 and β2 agonists, respectively) had similar effects on the NO response. In addition, the inhibitory effect of adrenaline on NO was abrogated by both propranolol (a non‐specific β blocker) and atenolol (a specific β1 inhibitor). In contrast to β receptor activation, the α adrenergic agonist phenylephrine had no effect on the LPS NO response, and furthermore, phentolamine (an α receptor antagonist) did not ameliorate adrenaline’s inhibitory action.
Mouse xenoantigens contribute to rat T‐cell Vβ repertoire generation in mixed xenogeneic bone marrow chimeras
Authors: Huang Y. , Ildstad S. T. , Neipp M. , Shirwan H.
Published: March 2003

We previously demonstrated that rat bone‐marrow‐derived cells in mixed xenogeneic chimeras (rat + mouse → mouse) contribute to peripheral selection of mouse T‐cell receptor (TCR) variable βs (Vβs) repertoire. In this study, we analysed rat T cells that developed in the chimeras to assess the contribution of mouse xenoantigens to the development of rat TCR repertoire. The expression of rat Vβs was analysed using flow cytometry and a reverse transcription–polymerase chain reaction (RT–PCR) method that allows for both semiquantitative analysis of rat Vβ gene expression and size heterogeneity of the complementarity determining region 3 (CDR3) domain. Three distinct patterns of Vβ expression were detected. Partial deletion was observed for Vβ5, 7, 12, 14, 16, 17 and 20 that exhibited reduced levels of peripheral expression by 3·4‐, 1·8‐, 8·7‐, 2·0‐, 7·8‐, 9·5‐ and 1·8‐fold, respectively, compared with the levels of Vβs in naïve rats. Higher levels of peripheral expression were detected for three rat Vβ genes; Vβ6 (2·2‐fold), Vβ8·2 (3·2‐fold), and Vβ9 (1·7‐fold). The relative expression of the other 10 known rat Vβ families in chimeras was unchanged as compared with that of normal rats. We did not observe detectable changes in the pattern of CDR3 expression in chimeras, suggesting that the mouse xenogeneic environment exerted its influence on the development of rat T cells via the Vβ‐encoded CDR1/2 domains. Our data demonstrate that the rat T‐cell repertoire in chimeras is shaped by both contractions as well as expansions of selected Vβs and suggest that mouse xenoantigens and/or superantigens of endogenous mouse retroviruses may contribute as ligands for these selection processes
Characterization of CD4– CD8– CD3+ T‐cell receptor‐αβ+ T cells in murine cytomegalovirus infection
Authors: Hossain M. S. , Takimoto H. , Ninomiya T. , Yoshida H. , Kishihara K. , Matsuzaki G. , Kimura G. , Nomoto K.
Published: March 2003

In this study, we have investigated that after the intraperitoneal infection with murine cytomegalovirus (MCMV), the CD3+ CD4– CD8–(double negative; DN) T‐cell receptor (TCR)αβ+ T cells increased in peritoneal cavity, liver and spleen in both resistant C57BL/6 and susceptible BALB/c mice. The total cellular population of these cells showed peak levels around day 5 after infection in all the three investigated organs and the following phenotypical and functional characteristics emerged. The peritoneal DN TCRαβ+ T cells expressed highly skewed TCRVβ8 on day 5 after infection compared with the uninfected mice, but those in spleen and liver showed moderate and low skewed TCRVβ8, respectively. The percentages of NK1.1+ DN TCRαβ+ T cells gradually decreased as did modulation of some of their activation markers consistent with an activated cell phenotype. The peritoneal DN TCRαβ+ T cells on day 5 after infection expressed the genes of interferon‐γ (IFN‐γ), tumour necrosis factor‐α, Eta‐1 (early T‐cell activation‐1) and MCP‐1 (monocyte chemoattractant protein 1) but lacked expression of interleukin‐4 (IL‐4). After in vitro stimulation with phorbol 12‐myristate 13‐acetate and calcium ionophore in the presence of Brefeldin A, higher frequencies of intracellular IFN‐γ+ DN TCRαβ+ T cells were detected in all three investigated organs of infected mice compared with those of uninfected mice. Stimulation of peritoneal DN TCRαβ+ T cells with plate‐bound anti‐TCRβ monoclonal antibodies showed proliferation and also produced IFN‐γ but not IL‐4. These results suggest that DN TCRαβ+ T cells were activated and may have an antiviral effect through producing IFN‐γ and some macrophage‐activating factors during an early phase of MCMV infection.
Immunity to vaginal herpes simplex virus‐2 infection in B‐cell knockout mice
Authors: Parr M. B. , Parr E. L.
Published: March 2003

We investigated the involvement of antibody in protection against vaginal herpes simplex virus type‐2 (HSV‐2) infection by comparing intact and B‐cell knockout (KO) mice. Vaginal immunization of intact mice with attenuated HSV‐2 markedly reduced an HSV‐2 challenge infection in the vagina. In contrast, immunization of B‐cell KO mice produced less immunity against the challenge infection and that immunity occurred in a different pattern. At 20 hr after challenge, immunostaining of virus proteins in the vaginal epithelium and shed virus protein titres in the vaginal secretions were not significantly different between immunized and non‐immunized B‐cell KO mice and were much greater than in immunized intact mice. At 48 hr after challenge, the vaginal infection in immunized B‐cell KO mice was markedly less than at 20 hr but remained ≈ sevenfold higher than in intact mice. This pattern of challenge infection in the vagina indicates that B cells, and probably the antibody derived from them, provided significant protection against reinfection in intact mice, especially during the first 20 hr after challenge, while other effector mechanisms became important between 20 and 48 hr after challenge. To determine whether T‐cell immunity in immunized B‐cell KO mice was equal to that in intact mice, we assessed interferon‐γ (IFN‐γ) secretion by memory T cells in vivo in the vagina at 20 hr after challenge. We found no significant differences in the up‐regulation of major histocompatibility complex (MHC) class II antigens in the epithelium, up‐regulation of vascular cell adhesion molecule‐1 (VCAM‐1) in vascular endothelium, or recruitment of T cells to the mucosa, indicating that the memory T‐cell response to virus challenge was the same in intact and B‐cell KO mice.
Calcitonin gene‐related peptide inhibits lipopolysaccharide‐induced interleukin‐12 release from mouse peritoneal macrophages, mediated by the cAMP pathway
Authors: Liu J. , Chen M. , Wang X.
Published: March 2003

Previously we showed that calcitonin gene‐related peptide (CGRP), a neuropeptide, inhibited lipopolysaccharide (LPS)‐induced tumour necrosis factor‐α (TNF‐α) production and increased interleukin (IL)‐6 release at low concentrations via activation of the cAMP pathway in mouse peritoneal macrophages (Mφ). In this study we examined whether CGRP could modulate IL‐12 release from mouse peritoneal Mφ, and if so, what signal transduction pathway was involved. Mφ were obtained from the peritoneal exudate of male BALB/c mice. The cells were plated on culture dishes at a density of 5 × 105 cells per well and allowed to adhere for 2 hr. After incubation for 24 hr, the Mφ were cultured with 0·1 µg/ml of LPS, alone or together with CGRP (1–1000 n
m) for 24 hr. The amount of IL‐12 in the cell medium was measured by enzyme‐linked immunosorbent assay (ELISA). The results showed that CGRP attenuated LPS‐induced IL‐12 release in a concentration‐dependent manner. Production of IL‐12 was decreased from 95·9 ± 4·6 to 73·4 ± 5·7 pg/ml by 100 n
m CGRP. The two cAMP phosphodiesterase (PDE) inhibitors, 3‐isobutyl‐1‐methyl‐xanthine (IBMX) and rolipram, significantly potentiated the CGRP response, and the level of IL‐12 was further decreased by 28% and 47%, respectively. However, CGRP had no effect on IL‐12 production from unstimulated Mφ. The LPS‐induced IL‐12 release from Mφ could also be reduced by forskolin, an activator of adenylate cyclase, and 8‐Br‐cAMP, an analogue of cAMP. Using the reverse transcription–polymerase chain reaction (RT–PCR), we found that CGRP also decreased the LPS‐induced IL‐12 p40 mRNA levels. Furthermore, pretreatment with H89 (0·1 µm or 1 µm), an inhibitor of cAMP‐dependent protein kinase, diminished CGRP effects, IL‐12 production and gene expression. These data suggest that LPS‐induced IL‐12 release and gene expression were attenuated by CGRP via an activated cAMP‐protein kinase A (PKA) pathway in mouse peritoneal Mφ.
Genetically detoxified mutants of heat‐labile enterotoxin from Escherichia coli are effective adjuvants for induction of cytotoxic T‐cell responses against HIV‐1 gag‐p55
Authors: Neidleman J. A. , Vajdy M. , Ugozzoli M. , Ott G. , O'hagan D.
Published: March 2003

There is an urgent need for prophylactic and therapeutic vaccines against human immunodeficiency virus (HIV). Mucosal immunization strategies have great potential to elicit both mucosal and systemic cellular immunity required to protect against HIV‐induced aquired immune deficiency syndrome (AIDS). However, mucosal immunizations with soluble protein antigens generally require adjuvants. In this study, we tested two mutants of the heat‐labile enterotoxin (LT) from Escherichia coli, LTK63: with no measurable ADP‐ribosyltransferase activity, and LTR72: with residual ADP‐ribosyltransferase activity, as mucosal adjuvants for induction of cytotoxic T lymphocyte (CTL) responses to coadministered HIV gag p55 protein. We found that intranasal (i.n.) immunizations with HIV gag p55 protein coadministered with LTK63 or LTR72 induced systemic CTL responses comparable to that obtained following intramuscular (i.m.) immunizations with the same adjuvants. Moreover, oral coadministration of LTR72, but not LTK63, resulted in local as well as systemic p55‐specific CTL responses in mesenteric lymph nodes (MLN) and spleens (SP) of the immunized mice. These data have important implications for current efforts to develop a safe vaccine against HIV.
Natural killer cell‐dependent immunoglobulin G2a anti‐bovine serum albumin (BSA) response elicited by high molecular weight dextran–BSA conjugates associated with dextran‐mediated macrophage–natural killer cell interaction
Authors: Ediriwickrema C. P. , Tonkonogy S. L. , Hammerberg B.
Published: March 2003

The roles of the interferon‐γ (IFN‐γ) and interleukin‐12 (IL‐12) produced during natural killer (NK) cell interaction with macrophages (Mφ) were investigated as the basis for the induction of immunoglobulin G2a (IgG2a) anti‐bovine serum albumin (BSA) responses by high molecular weight dextran conjugated to BSA (HMW‐DEX–BSA). BALB/c mice immunized with HMW‐DEX–BSA produced significantly higher levels of both IgG1 and IgG2a anti‐BSA than did mice immunized with BSA alone. Both IgG1 and IgG2a anti‐BSA levels were higher in mice immunized with BSA conjugated to dextran of molecular weight (MW) 5 000 000–40 000 000 compared with dextran of MW 10 000–60 000. The enhancement of anti‐BSA IgG2a levels but not of anti‐BSA IgG1 levels was inhibited when free BSA was added to the HMW‐DEX–BSA conjugate. NK cell depletion during HMW‐DEX–BSA immunization of mice resulted in significantly lower anti‐BSA IgG2a levels without affecting anti‐BSA IgG1 levels. Naive splenocytes or Mφ + NK cell co‐cultures incubated with HMW‐DEX or HMW‐DEX–BSA produced higher IFN‐γ levels than splenocytes or co‐cultures incubated with BSA alone. HMW‐DEX stimulated both IFN‐γ and IL‐12 production by Mφ + NK cell co‐cultures in a dose‐dependent manner. DEX‐induced IFN‐γ production by NK cells was dependent upon the presence of IL‐12, and IL‐12 production by Mφ was dependent upon the presence of IFN‐γ in these co‐cultures. Both Mφ and NK cells bound DEX to their surfaces. These data demonstrate that BSA linked to HMW‐DEX enhanced both T‐helper‐1‐ and T‐helper‐2‐associated antibody responses to BSA. The results also indicate an IL‐12‐dependent positive feedback interaction between NK cells and Mφ that supports a NK cell/IFN‐γ‐dependent mechanism for enhancement of anti‐BSA IgG2a antibody responses in mice immunized with HMW‐DEX–BSA protein conjugates.
Carcinogen‐modified dendritic cells induce immunosuppression by incomplete T‐cell activation resulting from impaired antigen uptake and reduced CD86 expression
Authors: Woods G. M. , Doherty K. V. , Malley R. C. , Rist M. J. , Muller H. K.
Published: March 2003

Exposure of the skin to environmental stimuli, such as chemical or physical carcinogens, modifies the local skin environment, including depletion of epidermal Langerhans’ cells (LC). Any subsequent exposure of the LC‐depleted skin to antigen results in the generation of antigen‐specific tolerance. In this study we evaluated the antigen‐bearing cells in the draining lymph nodes by capitalizing on the fluorescent nature of the contact sensitizer, fluorescein isothiocyanate (FITC). When FITC was applied to the skin of normal mice, two distinct populations of antigen‐bearing cells were identified in the draining lymph nodes. They were classified as either FITChi or FITClo on the basis of their fluorescence intensity and thus the amount of antigen they internalized. Only FITClo cells were detected in the lymph nodes draining FITC‐treated murine skin that had been depleted of epidermal LC by prior treatment with the complete carcinogen 9,10‐dimethyl 1,2‐benzanthracene (DMBA). Functional analysis of these cells revealed that the FITChi cells, but not the FITClo cells, induced antigen‐specific T‐cell proliferation. Further analysis of the FITClo cells from the DMBA‐treated mice demonstrated that these cells had reduced levels of CD80 expression, had substantially reduced levels of CD86 expression and performed poorly as co‐stimulator cells in an anti‐CD3‐mediated proliferative assay. Nonetheless these cells still induced early signs of T‐cell activation and interleukin‐12 production. Consequently the FITClo cells migrating from the LC‐depleted skin, through a combination of reduced antigen presentation and reduced co‐stimulatory activity, induced a state of unresponsiveness or anergy in the responder T cells in a similar manner to that observed when antigen presentation occurs in the absence of co‐stimulation. We propose that these unresponsive, or anergic cells, account for the antigen‐specific tolerance observed in these experiments.
DBA/2J (Mls‐1a) B‐cell differentiation in BALB.xid recipients
Authors: Tocce K. , Suppiah K. , Rago C. , Liberchuk R. , Duffy K. , Riggs J.
Published: March 2003

Studies of superantigens (SAg) have focused primarily on their impact on CD4+ T cells, largely bypassing the impact of the sequelae of this interaction upon the antigen‐presenting cell (APC). Sequelae of SAg‐induced CD4+ T‐cell activation include the ‘bathing’ of the SAg‐presenting cell with cytokines that promote the differentiation of the APC. In this report, the SAg‐induced differentiation of Mls+ DBA/2J B cells was studied in vivo by their transplantation into B‐cell‐defective BALB.xid recipients. Rapid, high‐level serum immunoglobulin M (IgM) production was noted shortly after transfer, disappearing by 3 weeks. Donor B cells, as evidenced after their chemical and genetic impairment and by the use of an IgM allotype‐disparate donor–recipient combination, contributed to this transient IgM production. These results clarify a discrepancy in the literature regarding donor B‐cell contribution to IgM production and illustrate a model system to utilize SAg to study B‐lymphocyte diversity.
Recessive expression of the H2A‐controlled immune response phenotype depends critically on antigen dose
Authors: Barcenas‐morales G. , Merkenschlager M. , Wahid F. , Döffinger R. , Ivanyi J.
Published: March 2003

Major histocompatibility complex (MHC) alleles acting as immune response genes are coexpressed in heterozygous individuals and therefore control of immune responses is usually codominant. As an exception to this rule, however, several examples of recessive immune responses have been ascribed to regulatory, e.g. suppressive, interactions. We report here that the recessive phenotype of both antibody and T‐cell responses to the mycobacterial 16 000‐MW antigen depends critically on a low antigen dose for immunization. On the basis of similar responses in hemi‐ and heterozygous mice, we suggest that the mechanism of recessive MHC control does not involve regulation by the low‐responder allele. We also demonstrated mixed haplotype restriction of peptide recognition for a significant fraction of high‐antigen‐dose primed T cells. Their paucity under limiting antigen dose conditions may lead to the recessive expression of MHC control. In conclusion, our results suggest that recessive MHC control can be explained as a simple gene dosage effect under conditions where antigen is limiting, without a need for regulatory mechanisms.
Human B‐cell lines constitutively express and secrete interleukin‐16
Authors: Sharma V. , Sparks J. L. , Vail J. D.
Published: March 2003

Interleukin‐16 (IL‐16), produced by activated CD8+ T lymphocytes, is inhibitory to human immunodeficiency virus‐1 (HIV‐1) replication. In an attempt to determine whether human B cells express and secrete IL‐16, a wide panel of B‐cell lines derived from patients with acquired immune deficiency syndrome (AIDS)‐associated B‐cell lymphomas (AABCL) (n = 5) and from non‐AABCLs (n = 8) were studied. Using reverse transcription–polymerase chain reaction (RT–PCR) analysis, we were able to observe ubiquitous expression of IL‐16 mRNA. Kinetic studies on constitutive mRNA turnover and secretion for IL‐16 suggests that the optimum expression is at 24 hr. Interestingly, we report, for the first time, IL‐16 secretion by human B‐cell lines.
T‐cell tolerance induction is normal in the (NZB × NZW)F1 murine model of systemic lupus erythematosus
Authors: Wither J. , Vukusic B.
Published: March 2003

The (New Zealand black (NZB) × New Zealand white (NZW))F1 (NZB/W) mouse strain spontaneously develops an autoimmune disease characterized by anti‐dsDNA antibody production and glomerulonephritis. Although evidence suggests that production of pathogenic autoantibodies is T‐cell dependent, the immunological defects that lead to activation of these autoreactive T cells are unknown. In particular, it has not been resolved whether autoreactive T cells become activated in these mice because of a generalized defect in T‐cell tolerance induction. Previous work has demonstrated that thymic and peripheral tolerance to strongly deleting antigens are intact in NZB/W mice. In this study we investigate whether these mice possess a more subtle T‐cell tolerance defect. To this end, we have produced NZB/W mice carrying a transgene encoding beef insulin (BI) which is expressed at levels close to the threshold for T‐cell tolerance induction. In BALB/c mice this transgene produces a profound but incomplete state of BI‐specific T‐cell tolerance, mediated predominantly by clonal anergy. Comparison of BI‐specific tolerance in NZB/W, major histocompatibility complex (MHC)‐matched (BALB/c × NZW)F1, and BALB/c BI‐transgenic mice clearly demonstrates that T‐cell tolerance induction is normal in NZB/W mice. The data suggest that the loss of T‐cell tolerance that ultimately supports nephritogenic autoantibody production in NZB/W mice does not result from a generalized defect in T‐cell tolerance, and by extension likely results from aberrant activation of specific autoreactive T cells.
Molecular remodelling of human CD46 for xenotransplantation: designing a potent complement regulator without measles virus receptor activity
Authors: Begum N. A. , Murakami Y. , Mikata S. , Matsumoto M. , Hatanaka M. , Nagasawa S. , Kinoshita T. , Seya T.
Published: March 2003

In pig‐to‐human discordant xenotransplantation, human complement (C) is a major barrier to long survival of xenografts. The current idea on how to cope with this barrier is that human complement regulatory proteins are forcibly expressed on xenografts to serve as safeguards against host C‐induced hyperacute rejection of xenografts. Co‐expression of decay‐accelerating factor (DAF) (CD55) and membrane cofactor protein (MCP) (CD46) would be the first choice for this trial, because most of the human cells are protected from C‐mediated damage by two different modes with these two kinds of C‐regulators. Many problems have arisen, however, for MCP expression on grafts. (i) MCP acts as a measles virus receptor, which may function to render donor pigs measles virus (MV) sensitive. (ii) MCP signals immune suppression which causes devastation of the recipient's immune responses. (iii) MCP exerts relatively low self‐protective activity against C compared with other cofactors; development of more efficient forms is desirable. (iv) Grafts with a high expression level of MCP are difficult to produce. In this study, we made a number of cDNA constructs of MCP, expressed them on swine endothelial cell lines, and tested cell‐protective potency and MV susceptibility. The short consensus repeat 1 (SCR1)‐deleted MCP with glycosyl phosphatidylinositol (GPI)‐anchored form (Δ1MCP‐PI) of MCP was found to be most suitable for the purpose of overcoming these problems. However, it was also found that MV induces two modes of cytopathic effect (CPE) on swine endothelial cells, either MCP‐dependent or ‐independent. Here, we discuss these two points which will be raised through study of MCP‐transgenic animals.
Capacity of mouse mast cells to prime T cells and to induce specific antibody responses in vivo
Authors: Villa I. , Skokos D. , Tkaczyk C. , Peronet R. , David B. , Huerre M. , Mécheri S.
Published: March 2003

Mouse, human and rat mast cells have been shown to express major histocompatibility complex II molecules and present antigens to specific T‐cell hybridomas in vitro. The purpose of our investigation was to determine whether mouse mast cells are able to initiate specific immune responses in vivo. Induction of anti‐dinitrophenyl (DNP) immunoglobulin G1 (IgG1) and IgG2a antibodies was performed by transferring ovalbumin (OVA)–DNP‐pulsed bone marrow‐derived mast cells (BMMC), B cells, or macrophages into naive mice which were boosted later with soluble antigen. Cultured spleen cells from immunized mice were tested for their cytokine content. Our data show that mast cells were by far better inducers of anti‐DNP IgG1 antibodies than were B cells and macrophages. In contrast, anti‐DNP IgG2a response induced by macrophages was much stronger than that obtained with mast cells whereas B cells were completely unable to elicit this response. In addition to a high index of cell proliferation, spleen cells from mast cell‐injected mice produced more interferon‐γ than those mice who received macrophages or B cells by two‐ to fivefold, and almost 10‐fold, respectively. Mast cell‐deficient Wf/Wf mice were compared with their normal +/+ littermates and with mast cell‐reconstituted Wf/Wf mice to develop delayed‐type hypersensitivity (DTH) reactions as well as humoral immune responses. Mast cell sufficient mice as well as mast cell‐reconstituted Wf/Wf mice developed significantly increased DTH reactions (P = 0·02, and 0·03, repectively) and higher anti‐OVA‐specific antibody responses as compared with Wf/Wf mice. Our data suggest that mast cells have the potential to up‐regulate both humoral and cellular immune responses in vivo.
Perpetuation of immunological memory: a relay hypothesis
Authors: Nayak R. , Mitra‐Kaushik S. , Shaila M. S.
Published: March 2003

A mechanism is proposed which explains the perpetuation of B‐cell immunological memory indefinitely without requiring the presence of long‐living memory cells or persisting antigen. The salient feature of this model is that immunological memory can be perpetuated indefinitely through the mutual interaction of idiotypic and anti‐idiotypic B cells. These cells mutually stimulate and clonally expand with either specific or bystander T‐cell help. Because B cells can present antigen, they present ‘apparently foreign’ idiopeptides to T cells. The idiopeptides of de novo synthesized antibody is presented to CD8+ T cells that recognize the idiopeptide‐presenting cell as targets and regulate their population. The recycling of immunoglobulins from surface to endosomal compartment of B cells leads to the presentation of idiopeptides by major histocompatibility complex (MHC) class II to CD4+ T cells. Even if the majority of the clonally expanded cells die because of lack of stimulation, cytotoxic T lymphocyte (CTL) lysis or for other reasons, the surviving cells will be able to carry forward the memory. This mechanism also provides a means for affinity maturation through idiotypic selection of somatically mutated high affinity cells or those from the naïve pool. We have termed these two types of complementary B cells as Burnet B cells: those which recognize the antigen or antigen mimic, and Jerne B cells, which can recognize the idiotypes of antibody and carry antigen mimics. The proposed hypothesis can explain differential duration of memory for different antigens, the shelf space paradox, affinity maturation, repertoire shift, etc.
Endocytosis and recycling of the complex between CD23 and HLA‐DR in human B cells
Authors: Karagiannis Sophia N. , Warrack John K. , Jennings Kevin H. , Murdock Paul R. , Christie Gary , Moulder Kevin , Sutton Brian J. , Gould Hannah J.
Published: March 2003

The presentation of extremely low doses of antigen to T cells is enhanced by immunoglobulin E (IgE)‐dependent antigen focusing to CD23, the low‐affinity receptor for IgE, expressed on activated B cells. CD23 contains a C‐type lectin domain in its extracellular sequence and a targeting signal for coated pits, required for endocytosis, in its cytoplasmic sequence. CD23 is non‐covalently associated with the major histocompatibility complex class II antigen, human leucocyte antigen HLA‐DR, on the surface of human B cells, but the fate of this complex following endocytosis is unknown. To answer this question we have labelled these proteins on the surface of RPMI 8866 B cells and traced their route through the cytoplasm. Endocytosis mediated by anti‐CD23 antibodies (BU38 and MHM6) led to the loss of CD23 from the cells. Endocytosis mediated by an antibody to HLA‐DR (CR3/43) or an antigen–IgE complex (NP‐BSA–anti‐NP IgE), however, led to recycling of the HLA‐DR–CD23 complex to the cell surface on a time scale (3–6 hr) consistent with the recycling of HLA‐DR in antigen presentation. Along the latter pathway CD23 label was observed in cytoplasmic organelles that resembled the ‘compartments for peptide loading’ or ‘class II vesicles’ described by previous authors. Two features of the recycling process may contribute to the efficiency of antigen presentation. Peptide exchange may be facilitated by the proximity of HLA‐DR and antigen in peptide loading compartments of the endosomal network. The return of CD23 with HLA‐DR to the cell surface may then help to stabilize specific B‐cell–T‐cell interactions, contributing to T‐cell activation.
Influence of ageing on Langerhans cell migration in mice: identification of a putative deficiency of epidermal interleukin‐1β
Authors: Cumberbatch Marie , Dearman Rebecca J. , Kimber Ian
Published: March 2003

Previous studies in mice have reported a decrease in epidermal Langerhans cell (LC) density in aged skin, however, the impact of this reduction on LC function and cutaneous immune responses is unclear. In the present series of experiments, the frequency of major histocompatibility complex class II+ LC in the epidermis of older (6‐month‐old) mice was found to be reduced significantly compared with that observed for young (6–8‐week‐old) mice. LC mobilization and the subsequent accumulation of dendritic cells (DC) in regional lymph nodes in response to topical challenge with a chemical allergen were found to be less vigorous in older mice. Flow cytometric analyses of DC derived from the draining lymph nodes of fluorescein isothiocyanate (FITC)‐sensitized mice revealed that the frequency of FITC+‐DC arriving in draining lymph nodes was also reduced in older mice but that the fluorescence intensity was comparable. Control and allergen‐treated‐older mice also displayed decreased total lymph node cellularity. Contact hypersensitivity responses were found not to be compromised in older mice. However, the cytokine regulation of LC migration in the two age groups of mice did differ. LC migration provoked by intradermal injection of tumour necrosis factor‐α (TNF‐α) was reduced in older animals, whereas, the percentage of LC that migrated in response to exogenous interleukin‐1β (IL‐1β) was comparable for both young and aged mice. Since both allergen‐ and TNF‐α‐induced LC responses are known to require receipt by LC of a signal from IL‐1β for effective migration, the suggestion is that impaired LC migration in older mice may be due to a reduced availability of epidermal IL‐1β.
Phosphodiester CpG oligonucleotides as adjuvants: polyguanosine runs enhance cellular uptake and improve immunostimulative activity of phosphodiester CpG oligonucleotides in vitro and in vivo
Authors: Dalpke Alexander H. , Zimmermann Stefan , Albrecht Inka , Heeg Klaus
Published: March 2003

Bacterial DNA and oligonucleotides (ODN) containing CpG‐motifs strongly activate cells of the immune system. Accordingly CpG‐DNA is a powerful adjuvant in vaccination protocols for B‐cell as well as for cytotoxic T‐cell responses. A decisive propensity of CpG‐DNA is its capacity to induce preferentially T helper type 1 (Th1)‐dominated immune responses. To exert its function CpG‐DNA has to be taken up by responsive cells, e.g. antigen‐presenting cells (APC). The rate of uptake is influenced by the DNA's backbone modification and critically determines activity of CpG‐DNA. CpG ODN with a phosphothioate backbone (PTO) are currently used for most in vivo and in vitro studies, since PTO modification protects ODN from the attack of nucleases. However, after administration of PTO‐modified CpG‐ODN long‐lasting effects including lymphadenopathy as well as sustained local interferon‐γ (IFN‐γ) and interleukin‐12 (IL‐12) production have been reported. To circumvent these restrictions we investigated the effects of DNA sequence as well as DNA backbone modification on cellular uptake and resulting immunostimulation. We show here that uptake of phosphodiester (PO)‐CpG‐ODN can be strongly enhanced by poly guanosine runs added at the 3′ end of the ODN. In addition these ODN showed an improved immunostimulatory activity in vivo and in vitro. This included protection of mice against lethal Th2‐dependent leishmaniasis as well as priming of antigen specific Th1 responses. More importantly, guanosine‐rich PO‐CpG‐ODN neither induced lymphadenopathy nor prolonged cytokine production after local administration. Since these improved PO ODN are efficient in vitro and in vivo and lack long lasting undesired effects they could be used preferably as adjuvants in vaccination protocols.
Accumulation of a potent γδ T‐cell stimulator after deletion of the lytB gene in Escherichia coli
Authors: Eberl Matthias , Altincicek Boran , Kollas Ann‐Kristin , Sanderbrand Silke , Bahr Ute , Reichenberg Armin , Beck Ewald , Foster Donald , Wiesner Jochen , Hintz Martin , Jomaa Hassan
Published: March 2003

Activation of human Vγ9/Vδ2 T cells by many pathogens depends on the presence of small phosphorylated non‐peptide compounds derived from the 2‐C‐methyl‐d‐erythritol 4‐phosphate (MEP) pathway of isoprenoid biosynthesis. We here demonstrate that in Escherichia coli mutants deficient in lytB, an essential gene of the MEP pathway, a potent Vγ9/Vδ2 T‐cell activator accumulates by a factor of approximately 150 compared to wild‐type E. coli. The compound responsible for the strong immunogenicity of this E. coli mutant was subsequently characterized and identified as a small pyrophosphorylated metabolite, with a molecular mass of 262 Da, derived from the MEP pathway. Stimulation of human peripheral blood mononuclear cells (PBMC) with extracts prepared from the lytB‐deficient E. coli mutant led to upregulation of T‐cell activation markers on the surface of Vγ9/Vδ2 T cells as well as proliferation and expansion of Vγ9/Vδ2 T cells. This response was dependent on costimulatory growth factors, such as interleukin (IL)‐2, IL‐15 and IL‐21. Significant levels of interferon‐γ (IFN‐γ) and tumour necrosis factor‐α (TNF‐α) were secreted in the presence of IL‐2 and IL‐15, but not in the presence of IL‐21, demonstrating that proliferating phosphoantigen‐reactive Vγ9/Vδ2 T cells do not necessarily produce proinflammatory cytokines.
Do functional subsets of leukocytes arise by divergent or linear differentiation?
Authors: Noble Alistair , Kemeny David M.
Published: March 2003

The T helper type 1 (Th1)/Th2 paradigm has been extended to a wide variety of leukocyte lineages since its inception, including innate immune cells such as dendritic cells and natural killer (NK) cells. Recently, studies of human NK cells have led to the proposition of a new model of linear differentiation in which cell phenotype is controlled by regulation of proliferation versus differentiation, rather than by divergent differentiation programmes. It was suggested that this model might also apply to T cells. Here we discuss the relevance of each model to different leukocyte lineages and argue that the linear differentiation model does not apply to αβ T cells.
Interleukin‐3, but not granulocyte–macrophage colony‐stimulating factor and interleukin‐5, inhibits apoptosis of human basophils through phosphatidylinositol 3‐kinase: requirement of NF‐κB‐dependent and ‐independent pathways
Authors: Zheng Xueyan , Karsan Aly , Duronio Vincent , Chu Fanny , Walker David C. , Bai Tony R. , Schellenberg R. Robert
Published: March 2003

Basophils are key effector cells of allergic reactions. Although proinflammatory cytokines, such as interleukin (IL)‐3, granulocyte–macrophage colony‐stimulating factor (GM–CSF) and IL‐5, inhibit eosinophil apoptosis in vitro, little is known about basophil apoptosis, and the signalling mechanisms required for basophil survival remain undefined. To address this issue, we used a novel negative‐selection system to isolate human basophils to a purity of > 95%, and evaluated apoptosis by morphology using light and transmission electron microscopy, and by annexin‐V binding and propidium iodide incorporation using flow cytometry. In this study, we demonstrated that the spontaneous rate of apoptotic basophils was higher than that of eosinophils as, at 24 hr, 57·6 ± 4·7% of basophils underwent apoptosis compared with 39·5 ± 3·8% of eosinophils. In addition, basophil cell death was significantly inhibited when cultured with IL‐3 for 48 hr (84·6 ± 4·9% vehicle‐treated cells versus 40·9 ± 3·9% IL‐3‐treated cells). IL‐3 also up‐regulated basophil CD69 surface expression. The effects of IL‐3 on apoptosis and CD69 surface expression of human basophils were completely blocked by LY294002 (LY), a potent inhibitor of phosphatidylinositol 3‐kinase (PI3‐K), but only partially inhibited by lactacystin, a proteasome inhibitor that prevents degradation of IκB and NF‐κB translocation. These observations reveal the novel finding that IL‐3 prevents basophil apoptosis through the activation of PI3‐K, which is only partially NF‐κB dependent. As basophils are active participants in allergic reactions and IL‐3 is one of the abundant proinflammatory cytokines in secretions from allergic tissue, we suggest that IL‐3‐mediated inhibition of basophil apoptosis may exacerbate the inflammation associated with allergic disorders.
Fibroblasts inhibit the production of interleukin‐12p70 by murine dendritic cells
Authors: Berthier Rolande , Rizzitelli Alexandra , Martinon‐Ego Catherine , Laharie Anne‐Marie , Collin Véronique , Chesne Serge , Marche Patrice Noël
Published: March 2003

Interleukin‐12 p70 (IL‐12p70) is a key cytokine produced by dendritic cells (DC) able to drive the development of T helper type 1 (Th1) lymphocytes. We showed that thymic and other fibroblasts strongly inhibit IL‐12p70 production by splenic DC stimulated by lipopolysaccharide plus either anti‐CD40 or interferon‐γ (IFN‐γ) and by purified splenic DC stimulated by Pansorbin plus IFN‐γ. This IL‐12p70 inhibitory activity is secreted in the conditioned medium of primary fibroblasts and fibroblast cell lines but not by haematopoietic cell lines. As IL‐10 was the unique factor able to inhibit IL‐12p70 produced by cultured splenic DC, we showed that a neutralizing antibody to IL‐10 did not suppress the IL‐12p70 inhibitory activity of thymic fibroblast‐conditioned medium (FCM). This FCM potently inhibits the maturation and expression of major histocompatibility complex class II and co‐stimulatory molecules induced by stimulation of spleen‐derived DC. While thymic FCM suppressed the IL‐12p70 expression by stimulated spleen‐derived DC, tumour necrosis factor‐α production is not affected. This inhibitory activity is able to down‐regulate the IL‐12p35 subunit transcription and expression, resulting in the impaired assembly of IL‐12p70 heterodimer. As fibroblasts are present in the tissue microenvironment and are active players in the establishment of an immune response, the nature and role of the fibroblastic inhibitory activity remain to be established.
Ethanol promotes T cell apoptosis through the mitochondrial pathway
Authors: Kapasi Aditi A. , Patel Geeta , Goenka Anuj , Nahar Nilay , Modi Neeraj , Bhaskaran Madhu , Reddy Krishna , Franki Nicholas , Patel Jaimita , Singhal Pravin C.
Published: March 2003

Clinical reports suggest that acute ethanol intoxication is often associated with lymphopenia. Previously, ethanol was reported to invoke thymocyte apoptosis. We studied the effect of ethanol on T cell apoptosis. In addition, we evaluated the molecular mechanism of ethanol‐induced T cell apoptosis. Human T cells harvested from healthy subjects after an alcohol drinking binge showed enhanced T cell apoptosis (before, 0·4 ± 0·2% versus after, 19·6 ± 2·5% apoptotic lymphocytes/field; P < 0·001). In in vitro studies, ethanol in a concentration of 50 mm and higher enhanced the apoptosis of Jurkat cells. DNA isolated from ethanol‐treated Jurkat cells displayed integer multiples of 180 base pairs. Ethanol decreased Jurkat cell expression of Bcl‐2, whereas ethanol increased Jurkat cell expression of Bax. Jurkat cells treated with ethanol also showed translocation of cytochrome C into cytosol. Moreover, a caspase‐9 inhibitor partially inhibited ethanol‐induced Jurkat cell apoptosis. In in vivo studies, after binge drinking, T cell expression of Bcl‐2 also decreased. In addition, binge drinking induced the cleavage of caspase‐3, suggesting activation of caspase‐3 in T cells. These results suggest that ethanol promotes T cell apoptosis through the activation of intrinsic or mitochondrial pathway.
Reinterpreting the demise of hierarchy: a case study in information technology, empowerment and incomplete contracts
Authors: Wareham Jonathan , Bjørn‐Andersen Niels , Neergaard Peter
Published: March 2003

This paper presents a case study of the implementation of a sophisticated internal performance monitoring system by the service division of a value‐added reseller of Canon products in Denmark. This new control system could not only aid in controlling cost and productivity but could also monitor customer service and quality levels. Although the new system was implemented with exceptional technical success, it met a very defensive reception among the technicians. In response, management decided to initiate an empowerment programme. In order for this programme to have a significant impact, management needed to make the requisite shifts from a strictly hierarchical to a team‐based organization form, as well as moving from a hierarchical to an interactive control process, it was only after the company completed this type of ‘organizational realignment’ that the real benefits of the system were harvested. This case study explores the implications of the dispersed and empowered organization and the consequent lack of direct process control, in order to fulfil this aim, the discussion is based on the Grossman, Hart and Moore theories of incomplete contracting and the role of ‘information assets’ and incentive misalignment of the newly ‘empowered’ and highly knowledge‐based service organization. Although property fights theories have typically been applied in ‘boundary of the firm’ questions, the goal of this case study is to illustrate the potential of incomplete contract theory in explaining internal incentive structures and governance mechanisms in the emerging wave of organizations characterized by a rich knowledge base, geographical dispersion, or even ‘loose’ and virtual organization structures.
The power of gifts: organizing social relationships in open source communities
Authors: Bergquist Magnus , Ljungberg Jan
Published: March 2003

Abstract. In writings on the open source software development model, it is often argued that it is successful as a result of the gift economy that embraces activities in online communities. However, the theoretical foundations for this argument are seldom discussed and empirically tested. Starting with the ‘classic’ theories of gift giving, we discuss how they need to be developed in order to explain gift‐giving practices in digital domains. In this paper, we argue that the gift economy is important, not only because it creates openness, but also because it organizes relationships between people in a certain way. Open source software development relies on gift giving as a way of getting new ideas and prototypes out into circulation. This also implies that the giver gets power from giving away. This power is used as a way of guaranteeing the quality of the code. We relate this practice to how gifts, in the form of new scientific knowledge, are given to the research community, and how this is done through peer review processes.