摘要:

AbstractFunctional high‐affinity interleukin‐2 receptors (IL‐2R) contain three transmembrane proteins, IL‐2Rα, β and γ. We have investigated the expression of IL‐2Rα and β genes in immature mouse thymocytes. Previous work has shown that during differentiation these cells transiently express IL‐2Rα on their surface. Stimulation of IL‐2Rα+and IL‐2Rα−immature thymocytes with phorbol 12‐myristate 13‐acetate and calcium ionophore induces synthesis of IL‐2Rα and IL‐2Rβ mRNA. Most of this response depends on autocrine stimulation by IL‐2. IL‐1 synergizes with IL‐2 to induce a 120‐fold increase in IL‐2Rα mRNA and a 14‐fold increase in IL‐2Rβ mRNA levels. A large proportion of the stimulated cells contains both transcripts. These interleukins do not induce any differentiation to more mature phenotypes. Collectively, these results show that IL‐2 plays a major role in the regulation of IL‐2R expression in normal immature thymocytes. We suggest that this response to interleukins may be part of a homeostatic mechanism to incre

ISSN:0014-2980    

DOI:10.1002/eji.1830240802

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractPrevious studies have suggested that T cell contact‐dependent signaling of macrophages (MΦ) is mediated by membrane tumor necrosis factor‐α (memTNF‐α), based on the observation that anti‐TNF‐α could inhibit T cell‐mediated MΦ activation. The current report confirms that anti‐TNF‐α does inhibit activation of interferon‐γ (IFN‐γ)‐primed MΦ by paraformaldehyde‐fixed activated T cells. However, the involvement of membrane molecules other than memTNF‐α in the contact‐dependent signaling is suggested by two lines of evidence. First, the TH2 clone, AK8, displayed neither secreted TNF‐α/β nor memTNF‐α/β detectable by bioassay or immunofluorescence. Nonetheless, AK8 cells were equally effective, on a per cell basis, in contact‐dependent signaling of MΦ activation as TH2 and TH1 cells which do express memTNF‐α. Second, the expression of memTNF‐α by the THclone, D10.G4, is maximal 24 h after activation, whereas the ability of this clone to activate MΦ is maximal at 6–8 h of activation and declines thereafter. Since TNF‐α is known to play a critical role in activation of MΦ effector function, it was hypothesized that T cell membrane components other than memTNF‐α might signal MΦ production of TNF‐α, thus allowing autocrine TNF‐α stimulation of MΦ effector function. In support of this, it is demonstrated that paraformaldehyde‐fixed activated TH2 cells can inducede novoproduction and release of TNF‐α by MΦ. This effect was not an artifactual result of paraformaldehyde fixation since paraformaldehyde‐fixed resting T cells did not induce TNF‐α gene expression. Previous studies have demonstrated a role for autocrine TNF‐α stimulation in LPS induction of effector function in recombinant IFN‐γ‐primed MΦ. The current study confirms that TNF‐α plays a critical role in T cell contact‐dependent signaling of MΦ but indicates that memTNF on the T cells may not be asine qua nonfactor for contact‐dependent signaling. The data suggest that other T cell membr

ISSN:0014-2980    

DOI:10.1002/eji.1830240803

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWe have previously described a model of tolerance to self peptides in a mouse transgenic (Tg) line producing secreted hen egg‐white lysozyme (HEL). The HEL cDNA was placed under the control of a ubiquitous promoter expressed early in embryogenesis, so that HEL should be present in Tg mice throughout the development of the immune system. Since individual HEL Tg mice express different amounts of serum HEL, we were previously able to show that H‐2dmice with HEL blood level>10 ng/ml are tolerant to HEL and to the immunodominant (ID) peptide 108–116. However, autoreactive T lymphocytes recognizing the HEL subdominant (SD) peptides 74–96 and 1–18 still persist and the SD‐specific responses disappear at higher blood HEL concentrations. In the present work, we have studied HEL Tg H‐2dmice with HEL serum levels<10 ng/ml (HEL‐low Tg animals). We find that 50% of Tg animals with HEL blood concentration<2 ng/ml are responsive to HEL in T cell proliferation assays, although these responses are lower than those seen in non‐Tg control mice. The HEL‐specific T lymphocytes react only with 15‐mer overlapping peptides encompassing the single H‐2dID region of HEL (residues 102–122); whereas the 9‐mer minimal ID peptide 108–116, which strongly triggers non‐Tg T cells, is unable to stimulate auto‐reactive T cellsin vitrofrom HEL‐low Tg mice. Altogether, our results suggest that T lymphocytes specific for the minimal ID peptide are deleted or inactivated, while T cell clones of lower affinity and reacting with epitopes on longer peptides persist. Thus, the high affinity ID peptide‐specific T cell clones can be negatively selected even

ISSN:0014-2980    

DOI:10.1002/eji.1830240804

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWe have performed extensive analyses of T cell receptor Vβ usage in the thymus, the spleen and the infiltrated islets of preclinical non‐obese diabetic (NOD) mice. A semiquantitative anchored polymerase chain reaction (An‐PCR) protocol has been developed for this purpose. The validity of the method has been first assessed by antibody staining with a panel of anti‐Vβ monoclonal antibodies (mAb). The results obtained by An‐PCR are accurate, reproducible, and in good agreement with cell surface protein staining. A strict comparison between thymus and spleen repertoires reveals no major Vβ‐specific deletion except the already reported Vβ3 deletion due to Mtv‐3. Certain Vβ such as Vβ15, 18, 20 are found with a low frequency in the spleen, but the fact that they are also scarce in the thymus probably reflects a poor availability of these genetic elements during β chain rearrangement rather than negative selection. Other Vβ, such as Vβ2, Vβ12 and Vβ14 are significantly more abundant in the spleen than in the thymus. This finding was confirmed by mAb staining for Vβ2 and Vβ14. The expansion asymetrically affects the CD4+subset and can be traced back to the mature, single‐positive thymocyte subset, suggesting an intrathymic positive selection event. Vβ repertoires in infiltrated islets of 13‐ and 18‐week‐old, non‐diabetic mice are polymorphic. Practically all the Vβ found in the peripheral lymphoid tissues are present in the islets, in similar proportions. The major exception is Vβ12, one of the Vβ which is subject to expansion during intrathymic differentiation and which is further augmented in the islets, both at 13 and 18 weeks. This increase probably reflects further peripheral amplification of the Vβ12‐bearing subset due to encounter with the same ligand as in the thymus or with a cross‐reactive motif. Finally, the nucleotide sequencing of all the Vβ segments in usage in the NOD strain confirms the absence

ISSN:0014-2980    

DOI:10.1002/eji.1830240805

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractOnly few infectious mouse mammary tumor viruses (MMTV) have been characterized which induce a potent superantigen responsein vivo.Here we describe the characterization of an MMTV which was isolated from milk of the highly mammary tumor‐prone SHN mouse strain. Exposure of newborn mice to milk‐borne MMTV (SHN) results in a very slow deletion of Vβ7, 8.1, 8.2 and 8.3 expressing peripheral T cells. Subcutaneous injection of adult mice with this virus induces a rapid and strong stimulation of all four affected Vβ‐subsetsin vivo.Besides the strong T cell effect we observed an early proliferation and activation of the local B cell pool leading to the initial secretion of IgM followed by preferential secretion of IgG2a, by day 6. Sequence comparison of the polymorphic C terminus with known open reading frames revealed high homology to the endogenous provirus Mtv‐RCS. This is the first report of a virus having a complete overlap in Vβ‐specificity with a bacterial superantigen stimulating as many as 35 % of the whole CD4+T cell repertoire inc

ISSN:0014-2980    

DOI:10.1002/eji.1830240806

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractAcute, low‐dose ultraviolet B (UVB) radiation alters the local skin site such that epicutaneous application of hapten fails to induce contact hypersensitivity (CH), but induces tolerance in UVB‐susceptible mice. Although the inability of irradiated skin to support CH induction may be a strictly local effect, there may also be systemic immune consequences of UVB radiation delivered in this manner. To examine this matter, abdominal skin of C57BL/6 mice was exposed to acute, low‐dose UVB radiation. Dinitrofluorobenzene was immediately painted directly on the irradiated site, or at a distant (unirradiated) site. In separate experiments, epicutaneous application of the hapten on a distant site was delayed for 1–3 days. The mice were tested for acquisition of CH, and for tolerance,i.e.the capacity to become sensitized when exposed subsequently to hapten via normal body wall skin. It was found that, immediately after completion of the UVB regimen, CH was inducible via unirradiated, but not via irradiated, skin. At 3 days post‐UVB exposure, CH was no longer inducible even through unirradiated skin. Mice that first encountered hapten via UVB‐exposed skin developed tolerance, as did mice that first encountered hapten viaunirradiatedskin of UVB‐treated mice. Neutralizing anti‐tumor necrosis factor‐α TNF‐α antibodies failed (a) to restore the ability of unirradiated skin to support induction of CH, and (b) to interfere with tolerance induction, whether hapten was first painted on irradiated or unirradiates skin. The data indicate that the acute, low‐dose regimen of UVB radiation produces effects on the immune system that are manifest locally as well as systemically. By demonstrating that the disruption of CH induction following UVB radiation is TNF‐α dependent, whereas locally and systemically induced tolerance is not, our findings encourage further search for other UVB‐related modulators of sys

ISSN:0014-2980    

DOI:10.1002/eji.1830240807

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractA study was performed to compare the use of immunoglobulin V gene segments by rheumatoid factors (RF) produced in physiological responses following a defined antigenic stimulus, with RF produced in rheumatoid arthritis (RA) and RF produced as monoclonal (M)‐components in certain lympho‐proliferative diseases. A panel of 46 monoclonal RF was produced, using hybridoma techniques, from healthy individuals following immunization with foreign antigens (mis‐matched red blood cells). A panel of previously characterized monoclonal RF from RA synovial tissues was extended to a total of 24 and included in the study. The variable heavy (VH) and variable light (VL) chain gene families used by these RF were determined using idiotypic markers and polymerase chain reaction amplification with VH‐specific primers. The frequencies of expression of the various gene families was compared between the two groups, and compared with the published expression frequencies seen amongst M‐component RF. The majority (87 %) of RF from healthy donors were found with light chains using V gene segments of the Vχ3 family, in conjunction with VHgene segments belonging to the VH1, VH3 and VH4 families. The over‐expression of Vχ3, together with the distribution of VHfamilies, demonstrates close similarities with RF found as M‐components in lympho‐proliferative diseases. In contrast, RF from RA patients showed a predominant use of VH3 gene segments (82 %) and an unbiased expression of Vχ3 segments (29 % of the light chains). These data suggest that RF found as M‐components are representative of RF used in normal physiological responses, but have undergone neoplastic or other transformation. RF found in the synovial tissue of RA patients appear to be driven by different mechanisms than RF seen in physiological responses in

ISSN:0014-2980    

DOI:10.1002/eji.1830240808

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractHere we report that soluble CD14 isolated from the urine of nephrotic patients (uCD14) contains a potent cytokine inducing activity. CD14 derived from urine appeared to consist of two major polypeptides of about 54 and 48 kDa. In uCD14 isolated from three different nephrotic patients the cytokine‐inducing activity appeared to co‐migrate with the 48‐kDa polypeptide which upon sequencing had the same N‐terminal sequence as native CD14. Treatment of human monocytes and the human astrocytoma cell line U373 with uCD14 resulted in a strong secretion of tumor necrosis factor (TNF) and interleukin‐6, respectively. The cytokine‐inducing activity of the uCD14 preparations was unaffected by the absence of serum. This is in contrast to the activation of human monocytes and U373 cells by lipopolysaccharide (LPS) which is highly dependent on the presence of serum. The cytokine‐inducing activity was not affected by LPS‐binding protein (LBP) or polyclonal rabbit antibodies against LBP The TNF‐inducing activity of uCD14 was also heat labile in contrast to the cytokine‐inducing activity of LPS, which was relatively heat resistant. The results suggest that CD14 may exist in at least two forms of which one is involved in

ISSN:0014-2980    

DOI:10.1002/eji.1830240809

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractPresent literature supports the view of an extrathymic origin for the subset of intestinal intraepithelial lymphocytes (IEL) that express the CD4−CD8+αα phenotype. This subset would include virtually all T cell receptor (TCR) γδ IEL and a portion of TCR αβ IEL. However, these reports do not exclude the possibility that some CD4−CD8+αα IEL are actually thymically derived. To clarify this issue, we examined the IEL day 3 neonatally thymectomized (NTX) mice. NTX resulted in as much as 80 % reduction in total TCR γδ IEL and in a nearly complete elimination of TCR αβ CD4−CD8+αα IEL early in ontogeny (3‐to 5‐week‐old mice). The thymus dependency of TCR γδ IEL and TCR αβ CD4−CD8+IEL was less prominent in older mice (7‐ to 10‐week‐old mice), as the total number of these IEL increased in NTX mice, but still remained severalfold less than that in euthymic mice. Furthermore, we demonstrate, by grafting the fetal thymus of CBF1 (H‐2b/d) mice under the kidney capsule of congenitally nude athymic mice of BALB/c background (H‐2d), that a substantial number of TCR γδ IEL and TCR αβ CD4−CD8+αα IEL can be thymically derived (H‐2b+). In contrast, but consistent with our NTX data, grafting of adult thymi into nude mice generated virtually no TCR γδ IEL and relatively less TCR αβ CD4−CD8+αα IEL than did the grafting of fetal thymi. These results suggest that the thymus is the major source of TCR γδ and TCR αβ CD4−CD8+αα IEL early in ontogeny, but that the extrathymic pathway is probably the major source of these IEL later in ontogeny. A reassessment of the

ISSN:0014-2980    

DOI:10.1002/eji.1830240810

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY

摘要:

AbstractWe have previously demonstrated that grafting of CBF1(H‐2b/d) fetal thymus (FTG) under the kidney capsule of congenitally athymic nude mice of BALB/c background (H‐2d) generates a substantial number of T cell receptor (TCR) γδ intestinal intraepithelial lymphocytes (IEL) that were of FTG origin (H‐2b+) (see accompanying report). Here we investigated the characteristics of these FTG‐derived TCR γδ IEL and compared them to the extrathymically derived TCR γδ IEL found in nude mice. Phenotypically, FTG‐derived TCR γδ IEL were similar to their extrathymically derived counterparts in that most were Thy‐1−, CD5−and CD8αα (homodimer). Vγ and Vδ gene usage in thymus‐derived and extrathymically derived TCR γδ IEL were found to be virtually the same. Functionally, FTG‐derived TCR γδ IEL were similar to the TCR γδ IEL found in euthymic mice as both were relatively anergic to TCR cross‐linkingin vitro.However, FTG‐derived TCR γδ IEL differed slightly from extrathymically derived TCR γδ IEL, which were completely nonresponsive to the samein vitrostimulation. Overall, these findings support the view that FTG‐derived and extrathymically derived TCR γδ IEL are almost indistinguishable. Lastly, we demonstrate that despite their thymic origin, development of FTG‐derived TCR γδ IEL partially takes place extrathymically; that is positive selection of FTG‐derived Vδ4 IEL occurs extrathymically. In addition, we demonstrate that the CD8 molecule is not necessary for development and homing of FTG‐derived TCR γδ IEL. This later finding suggests that the CD8αα mole

ISSN:0014-2980    

DOI:10.1002/eji.1830240811

出版商:WILEY‐VCH Verlag GmbH    

年代:1994

数据来源: WILEY