bluuebunny/crossref_metadata_2025 huggingface dataset:
Mimicry of the a determinant of hepatitis B surface antigen by an antiidiotypic antibody. I. Evaluation in hepatitis B surface antigen responder and nonresponder strains.
Authors: Pride M W , Thakur A , Thanavala Y
Published: June 2004

B and T cell responses of several strains of mice, immunized with a monoclonal antiidiotype (anti-Id) that mimics the a determinant of hepatitis B surface antigen (HBsAg), were studied to determine if the immune response to the anti-Id was regulated by H-2-linked immune response genes as has been previously observed for HBsAg. We report that immunization with anti-Id could elicit HBsAg-specific antibodies in mice of the H-2d,q, or f haplotype and in an outbred wild mouse strain (Mus spretus), thus circumventing the H-2 haplotype restriction pattern observed when immunizing with HBsAg in H-2f mice. Purified lymph node T cells from mice of the H-2d or q haplotype and M. spretus that were primed in vivo with HBsAg or anti-Id could be stimulated in vitro with either HBsAg or anti-Id but not with an irrelevant antibody of the same subclass as the anti-Id. However, purified lymph node T cells from H-2f mice that were primed in vivo with the anti-Id could only be stimulated in vitro with anti-Id. No in vitro stimulation whatsoever was observed in H-2f mice immunized with HBsAg. The effect of processing and presentation of the anti-Id by antigen-presenting cells (APC) was studied in mice of the H-2d haplotype. Stimulation of purified lymph node T cells by HBsAg and anti-Id was shown to be strictly dependent on APC and restricted by major histocompatibility complex class II antigens at the I-A locus. Treatment of APC with paraformaldehyde or chloroquine abrogated the T cell response to all antigens except for a nine-amino acid synthetic peptide representing a partial analogue of the group a determinant of HBsAg S(139-147). The significance of these results is discussed in the context of understanding the mechanism of mimicry elicited by the anti-Id.
Induction of alloantigen-specific hyporesponsiveness in human T lymphocytes by blocking interaction of CD28 with its natural ligand B7/BB1.
Authors: Tan P , Anasetti C , Hansen J A , Melrose J , Brunvand M , Bradshaw J , Ledbetter J A , Linsley P S
Published: June 2004

The specificity of T lymphocyte activation is determined by engagement of the T cell receptor (TCR) by peptide/major histocompatibility complexes expressed on the antigen-presenting cell (APC). Lacking costimulation by accessory molecules on the APC, T cell proliferation does not occur and unresponsiveness to subsequent antigenic stimulus is induced. The B7/BB1 receptor on APCs binds CD28 and CTLA-4 on T cells, and provides a costimulus for T cell proliferation. Here, we show that prolonged, specific T cell hyporesponsiveness to antigenic restimulation is achieved by blocking the interaction between CD28 and B7/BB1 in human mixed leukocyte culture (MLC). Secondary T cell proliferative responses to specific alloantigen were inhibited by addition to the primary culture of monovalent Fab fragments of anti-CD28 monoclonal antibody (mAb) 9.3, which block interaction of CD28 with B7/BB1 without activating T cells. Hypo-responsiveness was also induced in MLC by CTLA4Ig, a chimeric immunoglobulin fusion protein incorporating the extracellular domain of CTLA-4 with high binding avidity for B7/BB1. Cells previously primed could also be made hyporesponsive, if exposed to alloantigen in the presence of CTLA4Ig. Maximal hyporesponsiveness was achieved in MLC after 2 d of incubation with CTLA4Ig, and was maintained for at least 27 d after removal of CTLA4Ig. Accumulation of interleukin 2 (IL-2) and interferon gamma but not IL-4 mRNA was blocked by CTLA4Ig in T cells stimulated by alloantigen. Antigen-specific responses could be restored by addition of exogenous IL-2 at the time of the secondary stimulation. Addition to primary cultures of the intact bivalent anti-CD28 mAb 9.3, or B7/BB1+ transfected CHO cells or exogenous IL-2, abrogated induction of hyporesponsiveness by CTLA4Ig. These data indicate that interaction of CD28 with B7/BB1 during TCR engagement with antigen is required to maintain T cell competence and that blocking such interaction can result in a state of T cell hyporesponsiveness.
Putative prethymic T cell precursors within the early human embryonic liver: a molecular and functional analysis.
Authors: Sánchez M J , Gutiérrez-Ramos J C , Fernández E , Leonardo E , Lozano J , Martínez C , Toribio M L
Published: June 2004

Hematopoietic cells present in the liver in early human fetal life were characterized by phenotypic analysis using a broad panel of monoclonal antibodies. Expression of very late antigen 4 and leukocyte function-associated antigen 3 cell adhesion receptors and 4F2 cell activation molecules was found in all fetal liver hematopoietic cells before acquisition of T cell-, B cell-, or myeloid-specific surface markers, and before the time of intrathymic colonization. Molecular studies showed that expression of the interleukin 2 receptor beta (IL-2R beta) also occurred in the embryonic liver at this early ontogenic stage. In contrast, no expression of IL-2R alpha or IL-2 transcripts was found in fetal liver cells, whereas transcription of the IL-4 gene was detected in a small fetal liver cell subset. Putative T cell precursors were identified among the hematopoietic fetal liver cells by the expression of genes encoding the gamma, delta, epsilon, and zeta invariant chains of the CD3-T cell receptor (TCR) complex. However, no transcription of the polymorphic alpha and beta TCR genes was detected. Functional in vitro assays further demonstrated that fetal liver hematopoietic cells from those early embryos were capable of proliferating in response to T cell growth factors, including IL-4 and IL-2. However, whereas IL-4-induced proliferation paralleled the appearance in vitro of CD45+CD7-CD4dull cells expressing the CD14 myeloid antigen, as well as of CD34+ primitive hematopoietic progenitors, differentiation into CD45+CD7+CD8+CD3- immature T cells was observed when using IL-2. Moreover, coculture with thymic epithelial cell monolayers provided additional evidence that early fetal liver hematopoietic cells may include very primitive T cell precursors, which were able to differentiate in vitro into TCR alpha/beta+ mature T cells. Therefore, our results indicate that, after triggering of the T cell-specific maturation program in primitive fetal liver hematopoietic progenitors, specific signals provided intrathymically by epithelial cells may fulfill the requirements to drive terminal differentiation of prethymically committed T cell precursors.
Fas involvement in Ca(2+)-independent T cell-mediated cytotoxicity.
Authors: Rouvier E , Luciani M F , Golstein P
Published: June 2004

Mechanisms of T cell-mediated cytotoxicity remain poorly defined at the molecular level. To investigate some of these mechanisms, we used as target cells, on the one hand, thymocytes from lpr and gld mouse mutants, and on the other hand, L1210 cells transfected or not with the apoptosis-inducing Fas molecule. These independent mutant or transfectant-based approaches both led to the conclusion that Fas was involved in the Ca(2+)-independent component of cytotoxicity mediated by at least two sources of T cells, namely nonantigen-specific in vitro activated hybridoma cells, and antigen-specific in vivo raised peritoneal exudate lymphocytes. Thus, in these cases, T cell-mediated cytotoxicity involved transduction via Fas of the target cell death signal.
Very late antigen 4-dependent adhesion and costimulation of resting human T cells by the bacterial beta 1 integrin ligand invasin.
Authors: Ennis E , Isberg R R , Shimizu Y
Published: June 2004

Bacteria and viruses often use the normal biological properties of host adhesion molecules to infect relevant host cells. The outer membrane bacterial protein invasin mediates the attachment of Yersinia pseudotuberculosis to human cells. In vitro studies have shown that four members of the very late antigen (VLA) integrin family of adhesion molecules, VLA-3, VLA-4, VLA-5, and VLA-6, can bind to invasin. Since CD4+ T cells express and use these integrins, we have investigated the interaction of CD4+ T cells with purified invasin. Although VLA integrin-mediated adhesion of T cells to other ligands such as fibronectin does not occur at high levels unless the T cells are activated, resting T cells bind strongly to purified invasin. The binding of resting T cells to invasin requires metabolic activity and an intact cytoskeleton. Although CD4+ T cells express VLA-3, VLA-4, VLA-5, and VLA-6, monoclonal antibody (mAb) blocking studies implicate only VLA-4 as a T cell invasin receptor. Like other integrin ligands, invasin can facilitate T cell proliferative responses induced by a CD3-specific mAb. These results suggest that the nature of the integrin ligand is a critical additional factor that regulates T cell integrin activity, and that direct interactions of T cells with bacterial pathogens such as Yersinia may be relevant to host immune responses to bacterial infection.
Tyrosine phosphorylation of CD6 by stimulation of CD3: augmentation by the CD4 and CD2 coreceptors.
Authors: Wee S , Schieven G L , Kirihara J M , Tsu T T , Ledbetter J A , Aruffo A
Published: June 2004

When T cells are activated via the T cell receptor (TCR) complex a number of cellular substrates, including some cell surface proteins, become phosphorylated on tyrosine (Tyr) residues. Phosphorylation of cytoplasmic Tyr renders these cell surface receptors competent to interact with proteins that link cell surface receptors to protein in the intracellular signaling pathways. Here we show that Tyr residues in the cytoplasmic domain of CD6 become phosphorylated upon T cell activation via the TCR complex. Tyr phosphorylation was observed when the T cells were activated by crosslinking CD3 or by cocrosslinking CD3 with CD2 or CD4, but not when the cells were stimulated by crosslinking CD2, CD4, or CD28 alone. Unlike other Tyr kinase substrates, such as the phospholipase C gamma 1-associated pp35/36 protein, whose level of Tyr phosphorylation is highest when T cells are activated by cocrosslinking CD3 with CD2, the levels of CD6 Tyr phosphorylation are highest when T cells were activated by cocrosslinking CD3 with CD4.
Reversal of acute and chronic synovial inflammation by anti-transforming growth factor beta.
Authors: Wahl S M , Allen J B , Costa G L , Wong H L , Dasch J R
Published: June 2004

Transforming growth factor beta (TGF-beta) induces leukocyte recruitment and activation, events central to an inflammatory response. In this study, we demonstrate that antagonism of TGF-beta with a neutralizing antibody not only blocks inflammatory cell accumulation, but also tissue pathology in an experimental model of chronic erosive polyarthritis. Intraarticular injection of monoclonal antibody 1D11.16, which inhibits both TGF-beta 1 and TGF-beta 2 bioactivity, into animals receiving an arthropathic dose of bacterial cell walls significantly inhibits arthritis. Inhibition was observed with a single injection of 50 micrograms antibody, and a 1-mg injection blocked acute inflammation > 75% compared with the contralateral joints injected with an irrelevant isotype control antibody (MOPC21) as quantitated by an articular index (AI = 0.93 +/- 0.23 for 1D11.16, and AI = 4.0 +/- 0 on day 4; p < 0.001). Moreover, suppression of the acute arthritis achieved with a single injection of antibody was sustained into the chronic, destructive phase of the disease (on day 18, AI = 0.93 +/- 0.07 vs. AI = 2.6 +/- 0.5; p < 0.01). The decreased inflammatory index associated with anti-TGF-beta treatment was consistent with histopathologic and radiologic evidence of a therapeutic response. These data implicate TGF-beta as a profound agonist not only in the early events responsible for synovial inflammation, but also in the chronicity of streptococcal cell wall fragment-induced inflammation culminating in destructive pathology. Interrupting the cycle of leukocyte recruitment and activation with TGF-beta antagonists may provide a mechanism for resolution of chronic destructive lesions.
Delayed hematopoietic development in osteopetrotic (op/op) mice.
Authors: Begg S K , Radley J M , Pollard J W , Chisholm O T , Stanley E R , Bertoncello I
Published: June 2004

Changes in structure, cellularity, hematopoietic progenitor cell and macrophage content, and osteoclast activity were investigated in the hematopoietic organs of the colony-stimulating factor 1(CSF-1)-less osteopetrotic (op/op) mouse. The data indicated that op/op mice undergo an age-related hematopoietic recovery and resolution of osteopetrosis, suggesting that the hematopoietic system has the capacity to use alternative mechanisms to compensate for the absence of an important multifunctional growth factor, CSF-1. In young animals, op/op femurs were heavily infiltrated with bone, and marrow cellularity was significantly reduced. After 6 wk of age, there was an increase in the marrow space available for hematopoiesis. The femoral cavity of op/op mice progressively enlarged, and by 22 wk of age its appearance and marrow cellularity was comparable to that of controls. The percentage of op/op mononuclear phagocytes, defined by F4/80 antigen expression, progressively increased to normal levels by 35 wk of age. There was no difference in the incidence of both primitive and mononuclear phagocyte-committed, CSF-1-responsive progenitor cells in op/op marrow, but their femoral content was significantly reduced in young mice. During the period of reduced hematopoiesis in the marrow of young op/op mice, splenic hematopoietic activity was elevated. This mutant mouse represents a system for the study of the CSF-1-independent regulatory mechanisms involved in hematopoietic regulation.
Human neutrophils express immunoglobulin E (IgE)-binding proteins (Mac-2/epsilon BP) of the S-type lectin family: role in IgE-dependent activation.
Authors: Truong M J , Gruart V , Kusnierz J P , Papin J P , Loiseau S , Capron A , Capron M
Published: June 2004

It has been suggested that neutrophils may be involved in the late-phase reaction of immunoglobulin E (IgE)-dependent hypersensitivity states. However, the identity of neutrophil-associated molecules inducing the release of mediators remains unclear. In this report, we demonstrate that human neutrophils from normal donors or from patients with inflammatory disorders could bind myeloma IgE proteins, especially after desialylation. Northern blot, immunoprecipitation, and flow cytometry analyses revealed that neutrophils did not express Fc epsilon RII/CD23, but rather Mac-2/epsilon binding protein (BP), belonging to the S-type lectin family. Similarly to IgA used as positive control, myeloma IgE proteins, as well as polyclonal IgE antibodies with or without antibody specificity, were both capable of inducing a neutrophil respiratory burst. Anti-Mac-2 but not anti-CD23 mAb strongly decreased the IgE-dependent activation of neutrophils, induced either by the specific antigen or by anti-IgE antibodies. These findings open new perspectives on the functional role of neutrophils in IgE-associated diseases including allergic states or parasitic infections.
Major histocompatibility complex-specific prolongation of murine skin and cardiac allograft survival after in vivo depletion of V beta+ T cells.
Authors: Goss J A , Pyo R , Flye M W , Connolly J M , Hansen T H
Published: June 2004

The preferential usage of certain T cell receptor (TCR) V beta genes has been well established in several major histocompatibility complex (MHC)-restricted immune responses. However, V beta usage among allogeneic responses remains unclear. Because recent findings of ours and others indicate that V beta 8 predominates in certain Ld-restricted, peptide-specific responses, we examined the V beta 8 usage in allogeneic responses to Ld. To selectively recognize the Ld molecule, cells from BALB/c-H-2dm2 (dm2), the Ld-loss mutant mouse, were stimulated in vitro or in vivo with wild-type BALB/c cells. We report here that after the intraperitoneal administration of the anti-V beta 8 monoclonal antibody (mAb) F23.1, peripheral V beta 8 T cells were depleted from dm2 mice. This in vivo depletion abrogated the ability of dm2 splenocytes to mount a primary response to Ld molecules. This abrogation was specific, since the response of V beta 8-depleted dm2 cells to Kb/Db antigens was the same as that of control nondepleted dm2 cells. Furthermore, in vivo depletion of V beta 8 cells was found to cause a dramatic prolongation of Ld-disparate skin grafts (mean survival time [MST] 22.1 +/- 2.1 vs. 10.3 +/- 1.1 d for saline-treated controls, or 10.9 +/- 1.7 d for controls treated with mAb KJ23 to V beta 17). By contrast, V beta 8 depletion had no effect on recipients grafted with haplotype-mismatched skin or single Dk-locus-disparate skin. These findings demonstrate that V beta 8+ T cells predominate in allogeneic response to Ld but not other alloantigens. The effect of V beta 8 depletion was found to be even more dramatic on recipients grafted with Ld-disparate vascularized heart transplants (MST > 100 vs. 8.6 +/- 0.5 d for controls). In total, these findings establish the efficacy of using mAb to the V beta gene family to specifically and significantly enhance the survival of allografts. The implications of detecting V beta 8 usage in both alloreactive or MHC-restricted TCR responses to the same class I molecule are discussed.
Conventional B cells, not B-1 cells, are responsible for producing autoantibodies in lpr mice.
Authors: Reap E A , Sobel E S , Cohen P L , Eisenberg R A
Published: June 2004

Mice homozygous for the lpr gene develop autoantibodies and polyclonal B cell activation similar to what is seen in human systemic lupus erythematosus patients. We have previously shown that an lpr-specific intrinsic B cell defect was necessary for autoantibody production in this model. In the current study, we have further defined these autoantibody-producing B cells. Two major subsets of B cells have been described. B-1 cells (CD5+ B cells) can be distinguished from conventional B cells on the basis of phenotype, cytokine secretion, gene expression, anatomical location, and function. In addition, B-1 cells have been implicated in autoimmunity in several murine and human studies. To address the question of which B cell subset produces autoantibodies in lpr mice, we used immunoglobulin heavy chain (Igh) allotype-marked peritoneal (B-1 cell source) and bone marrow (conventional B cell source) cells from lpr mice to establish B cell chimeras. We used two general approaches. In one, we reconstituted sublethally irradiated mice with B-1 cells of one allotype and bone marrow cells of another allotype. In the second method, we suppressed endogenous B cells in neonatal mice with allotype-specific anti-IgM antibody, and injected peritoneal cells of another allotype. After antibody treatment was stopped, the mouse's conventional B cells recovered, but the B-1 subset was only reconstituted by the donor. In both types of chimeras, antichromatin, rheumatoid factor, and anti-single stranded DNA (ssDNA) autoantibodies were produced by the conventional B cell bone marrow source. In addition, an age-related decrease in peritoneal B-1 cells was seen, even in unmanipulated lpr mice. These data show that lpr B-1 cells are not important producers of autoantibodies. Conventional B cells are the source of autoantibodies directed at chromatin, ssDNA, and IgG.
Site-specific alterations in the B oligomer that affect receptor-binding activities and mitogenicity of pertussis toxin.
Authors: Lobet Y , Feron C , Dequesne G , Simoen E , Hauser P , Locht C
Published: June 2004

Pertussis toxin plays a major role in the pathogenesis of whooping cough and is considered an important constituent of vaccines against this disease. It is composed of five different subunits associated in a molar ratio 1S1:1S2:1S3:2S4:1S5. The S1 subunit is responsible for the ADP-ribosyltransferase activity of the toxin. The B moiety, composed of S2 through S5, recognizes and binds to the target cell receptors and has some ADP-ribosyltransferase-independent activities such as mitogenicity. Site-directed mutagenesis of subunits S2 and S3 allowed us to identify amino acid residues involved in receptor binding. Of all the modifications generated, the deletion of Asn 105 in S2 and of Lys 105 in S3 resulted in the more drastic reduction of binding to haptoglobin and CHO cells, respectively. A holotoxin carrying both deletions presented a mitogenicity reduced to an undetectable level. The combination of these B oligomer mutations with two substitutions in the S1 subunit led to the production of a toxin analog with reduced ADP-ribosyltransferase-dependent and -independent activities including mitogenicity. As shown by immunoprecipitation with various monoclonal antibodies, the mutant holotoxin was correctly assembled and antigenically similar to the native toxin. This toxin analog induced toxin-neutralizing antibodies at the same level as the holotoxin carrying only mutations in the S1 subunit, and may therefore be considered a useful candidate for the development of a new generation vaccine against whooping cough.
The major histocompatibility complex-restricted response of recombinant inbred strains of mice to natural tick transmission of Borrelia burgdorferi.
Authors: Golde W T , Burkot T R , Sviat S , Keen M G , Mayer L W , Johnson B J , Piesman J
Published: June 2004

The causative agent of Lyme disease, Borrelia burgdorferi, is transmitted by ticks of the Ixodes ricinus complex. In this study, we report the antibody response of recombinant inbred strains of mice of the H-2, b, d, and k haplotypes, infected with B. burgdorferi as a result of exposure to infected I. dammini. The patterns of antibody response assayed by Western blot analysis indicate significant major histocompatibility complex (MHC) restriction to bacterial antigens within the first 2 mo of infection in mice. Other bacterial antigens induce a significant response across the MHC haplotypes tested when assayed on the same bacterial strain used to transmit the infection, but do not crossreact with the same proteins derived from heterologous strains of B. burgdorferi. No response to outer surface protein A was detected at any time during the 60-d period we analyzed this infection. A third group of bacterial antigens appear to generate a MHC-nonrestricted response, and this lack of restriction is maintained when assaying the crossreactivity of the response with other strains of B. burgdorferi. These proteins may provide more accurate diagnostic probes than those currently in use. Finally, there appears to be a significant difference in the expression of most bacterial antigens when the spirochete is cultured for many passages since the same strain of bacterium isolated from low-passage and high-passage preparations exhibit different banding patterns in Western blots when assayed with the same sera.
Molecular evolution of the human immunoglobulin E response: high incidence of shared mutations and clonal relatedness among epsilon VH5 transcripts from three unrelated patients with atopic dermatitis.
Authors: van der Stoep N , van der Linden J , Logtenberg T
Published: June 2004

We have analyzed the nucleotide sequences of 19 epsilon VH5 transcripts derived from in vivo isotype switched peripheral blood B cells of three patients with atopic dermatitis. Comparison with the patients' own germline VH5 gene segments revealed that the epsilon transcripts were derived from both functional members of the human VH5 gene family and harbored numerous somatic mutations (range 5-36 per VH5 gene). In two patients, we detected clonally related but diverged transcripts, permitting the construction of a genealogical tree in one patient. We observed a high proportion of shared silent (S) and replacement (R) mutations among epsilon VH5 sequences derived from all three individuals, even among transcripts descending from the two different germline VH5 gene segments. A remarkably high number of these mutations is shared with previously reported VH5 genes encoding antibodies with defined specificities. The shared S mutations, and likely a fraction of the R mutations, appear to mark preferential sites ("hot spots") of somatic hypermutations in human VH5 genes. The distribution of R and S mutations over complementarity determining region and framework regions in the majority of VH regions deviated from that characteristic of antigen-driven immune response. We hypothesize that the V regions of immunoglobulin E-bearing B cells have accumulated "selectively neutral" mutations over extended periods of clonal expansion, resulting in unusual R/S ratios. We propose that the molecular characteristics of the epsilon VH regions in atopic dermatitis may be representative of antigens that recurrently or chronically stimulate the immune system.
Thymic origin of embryonic intestinal gamma/delta T cells.
Authors: Dunon D , Cooper M D , Imhof B A
Published: June 2004

Current evidence suggests both thymic and extrathymic origins for T cells. Studies in mice favor an in situ origin for a prominent population of intestinal intraepithelial lymphocytes that express gamma/delta T cell receptor (TCR). This developmental issue is explored in an avian model in which the gamma/delta lymphocytes constitute a major T cell subpopulation that is accessible for study during the earliest stages of lymphocyte development. In the chick embryo, cells bearing the gamma/delta TCR appear first in the thymus where they reach peak levels on days 14-15 of embryogenesis, just 2 d before gamma/delta T cells appear in the intestine. Using two congenic chick strains, one of which expresses the ov antigen, we studied the origin and kinetics of intestinal colonization by gamma/delta T cells. The embryonic gamma/delta+ thymocytes homed to the intestine where they survived for months, whereas an embryonic gamma/delta- thymocyte population enriched in thymocyte precursors failed to give rise to intestinal gamma/delta+ T cells. Embryonic hemopoietic tissues, bone marrow, and spleen, were also ineffective sources for intestinal gamma/delta+ T cells. Intestinal colonization by gamma/delta+ thymocytes occurred in two discrete waves in embryos and newly hatched birds. The data indicate that intestinal gamma/delta T cells in the chicken are primarily thymic migrants that are relatively long-lived.
Identification of human cancers deficient in antigen processing.
Authors: Restifo N P , Esquivel F , Kawakami Y , Yewdell J W , Mulé J J , Rosenberg S A , Bennink J R
Published: June 2004

Intracellular antigens must be processed before presentation to CD8+ T cells by major histocompatibility complex (MHC) class I molecules. Using a recombinant vaccinia virus (Vac) to transiently express the Kd molecule, we studied the antigen processing efficiency of 26 different human tumor lines. Three cell lines, all human small cell lung carcinoma, consistently failed to process endogenously synthesized proteins for presentation to Kd-restricted, Vac-specific T cells. Pulse-chase experiments showed that MHC class I molecules were not transported by these cell lines from the endoplasmic reticulum to the cell surface. This finding suggested that peptides were not available for binding to nascent MHC molecules in the endoplasmic reticulum. Northern blot analysis of these cells revealed low to nondetectable levels of mRNAs for MHC-encoded proteasome components LMP-7 and LMP-2, as well as the putative peptide transporters TAP-1 and TAP-2. Treatment of cells with interferon gamma enhanced expression of these mRNAs and reversed the observed functional and biochemical deficits. Our findings suggest that downregulation of antigen processing may be one of the strategies used by tumors to escape immune surveillance. Potential therapeutic applications of these findings include enhancing antigen processing at the level of the transcription of MHC-encoded proteasome and transporter genes.
Epstein-Barr virus transformation induces B lymphocytes to produce human interleukin 10.
Authors: Burdin N , Péronne C , Banchereau J , Rousset F
Published: June 2004

Interleukin 10 (IL-10) is a pleiotropic factor that enhances proliferation of activated human B lymphocytes and induces them to secrete high amounts of immunoglobulins. Here we show that several human B cell lines were able to constitutively secrete human (h)IL-10. Whereas none of the pre-B nor the plasmocytic cell lines tested produced hIL-10, 25 of the 36 tested mature B cell lines (lymphoblastoid and Burkitt lymphoma cell lines) secreted hIL-10. Moreover, 24 of these 25 hIL-10-producing B cell lines contained the Epstein-Barr virus (EBV) genome, suggesting a relationship between hIL-10 production by human B cell lines and EBV expression. Accordingly, whereas polyclonal activation via triggering of surface immunoglobulins or CD40 antigen induced highly purified normal human B lymphocytes to produce only low (0.3-0.4 ng/ml) but significant amounts of hIL-10, EBV infection induced them to secrete high amounts of hIL-10 (4-9 ng/ml). Furthermore, addition of exogenous hIL-10, simultaneously to EBV infection, potentiated cell proliferation, whereas a blocking anti-IL-10 antiserum inhibited it. Thus, hIL-10 produced by infected human B lymphocytes appears to be involved in the mechanisms of EBV-induced B cell proliferation.
High frequency of cross-reactive cytotoxic T lymphocytes elicited during the virus-induced polyclonal cytotoxic T lymphocyte response.
Authors: Nahill S R , Welsh R M
Published: June 2004

Polyclonal stimulation of CD8+ cytotoxic T lymphocytes (CTL) occurs during infection with many viruses including those not known to transform CTL or encode superantigens. This polyclonal CTL response includes the generation of high levels of allospecific CTL directed against many class I haplotypes. In this report we investigated whether the allospecific CTL generated during an acute lymphocytic choriomeningitis virus (LCMV) infection of C57BL/6 mice were stimulated specifically by antigen recognition or nonspecifically by polyclonal mechanisms possibly involving lymphokines or superantigens. An examination of the ability of different strains of mice to induce high levels of CTL specific for a given alloantigen showed that most, but not all, strains generated high levels of allospecific CTL, and that their abilities to generate them mapped genetically to the major histocompatibility complex locus, exclusive of the class II region. This indicated that the virus-induced allospecific CTL generation was independent of the class II allotype, and mice depleted of CD4+ cells generated allospecific CTL, indicating independence of class II-CD4+ cell interactions and resulting CD4+ cell-secreted lymphokines. FACS staining with a variety of V beta-binding antibodies did not show a superantigen-like depletion or enrichment of any tested V beta + subset during infection. Several experiments provided evidence in support of direct stimulation of CD8+ cells via the T cell receptor: (a) both virus- and allo-specific killing were enriched within a given V beta subpopulation; (b) relative CTL precursor frequencies against different class I alloantigens changed during the course of virus infection; (c) the relative levels of virus-induced, allospecific CTL-mediated lysis at day 8 after infection did not parallel the CTL precursor frequencies before infection; and (d) limiting dilution analyses of day 8 LCMV-infected spleen cells stimulated by virus-infected syngeneic peritoneal exudate cells (PEC) revealed not only the expected virus-specific CTL clones, but also a high frequency of clones that were cross-reactive with allogeneic and virus-infected syngeneic targets. In addition to the virus cross-reactive allospecific CTL clones, virus-infected PEC also stimulated the generation of some allospecific clones that did not lyse virus-infected fibroblasts. Surprisingly, LCMV-infected PEC were much more efficient at stimulating allospecific CTL clones from day 8 LCMV-infected splenocytes than were allogeneic stimulators. These results indicate that at least part of the polyclonal allospecific CTL response elicited by acute virus infection is a consequence of the selective expansion of many clones of allospecific CTL which cross-react with virus-infected cells.(ABSTRACT TRUNCATED AT 400 WORDS)
Restricted immunoglobulin junctional diversity in neonatal B cells results from developmental selection rather than homology-based V(D)J joining.
Authors: Pandey A , Tjoelker L W , Thompson C B
Published: June 2004

The mechanism by which coding ends are joined during immunoglobulin (Ig) recombination is poorly understood. Recently, short sequence similarities (2-6 bp) observed at the ends of certain variable (V), diversity (D), and joining (J) gene segments of Ig have been correlated with limited junctional diversity observed in coding exons assembled from these elements. However, it is unclear whether these sequence homologies play any direct role in favoring coding joint formation by influencing the V(D)J recombination process. In this report, we demonstrate that coding sequence similarities do not influence the position of coding joints during V(D)J recombination in vivo. Instead, during embryonic development, B cells with certain joining products undergo progressive selection. Developmental selection is completed before exposure to external antigens and appears to be determined by the amino acid sequence encoded by the coding joint. We conclude that the nucleotide sequences of the coding regions do not play a major role in directing V(D)J recombination. Instead, we propose that limited Ig junctional diversity results from prenatal developmental selection of B cells based on the protein sequence of their surface Ig antigen-binding site. Sequence identities at the ends of coding segments may have evolved because they increase the likelihood that a selectable antigen-binding site is created during a random recombination process.
Epstein-Barr virus and Hodgkin's disease: transcriptional analysis of virus latency in the malignant cells.
Authors: Deacon E M , Pallesen G , Niedobitek G , Crocker J , Brooks L , Rickinson A B , Young L S
Published: June 2004

Epstein-Barr virus (EBV) is associated with a number of different human tumors and appears to play different pathogenetic roles in each case. Thus, immunoblastic B cell lymphomas of the immunosuppressed display the full pattern of EBV latent gene expression (expressing Epstein-Barr nuclear antigen [EBNA]1, 2, 3A, 3B, 3C, and -LP, and latent membrane protein [LMP]1, 2A, and 2B), just as do B lymphoblastoid cell lines transformed by the virus in vitro. In contrast, those EBV-associated tumors with a more complex, multistep pathogenesis show more restricted patterns of viral gene expression, limited in Burkitt's lymphoma to EBNA1 only and in nasopharyngeal carcinoma (NPC) to EBNA1 and LMP1, 2A, and 2B. Recent evidence has implicated EBV in the pathogenesis of another lymphoid tumor, Hodgkin's disease (HD), where the malignant Hodgkin's and Reed-Sternberg (HRS) cells are EBV genome positive in up to 50% of cases. Here we extend preliminary results on viral gene expression in HRS cells by adopting polymerase chain reaction-based and in situ hybridization assays capable of detecting specific EBV latent transcripts diagnostic of the different possible forms of EBV latency. We show that the transcriptional program of the virus in HRS cells is similar to that seen in NPC in several respects: (a) selective expression of EBNA1 mRNA from the BamHI F promoter; (b) downregulation of the BamHI C and W promoters and their associated EBNA mRNAs; (c) expression of LMP1 and, in most cases, LMP2A and 2B transcripts; and (d) expression of the "rightward-running" BamHI A transcripts once thought to be unique to NPC. This form of latency, consistently detected in EBV-positive HD irrespective of histological subtype, implies an active role for the virus in the pathogenesis of HD and also suggests that the tumor may remain sensitive to at least certain facets of the EBV-induced cytotoxic T cell response.
Production and characterization of an Mls-1-specific monoclonal antibody.
Authors: Mohan N , Mottershead D , Subramanyam M , Beutner U , Huber B T
Published: June 2004

Superantigens (SAGs) represent a new class of antigens, characterized as T cell receptor (TCR) V beta-reactive elements. Bacterial toxins constitute the major group of exogenous SAGs, while the mouse mammary tumor virus (MMTV)-encoded Mls molecules represent the endogenous SAGs. Mls-1 is the prototype of the latter SAGs, because it elicits a very potent T cell stimulatory response in vitro in unprimed T cells expressing the TCR V beta 6 or 8.1 chains. In vivo, Mls-1 causes deletion of immature T cells bearing the V beta 6, 7, 8.1, or 9 chains. Although Mls-1 was functionally discovered > 20 yr ago, it has not been possible to raise antibodies against this molecule. We have previously cloned and sequenced the Mtv-7 sag gene, which encodes Mls-1. Sequence comparisons with other MMTV sag genes suggested that the polymorphic 3' end encodes the TCR V beta specificity of these SAGs. We have, therefore, immunized hamsters with a 14-amino acid peptide from the deduced COOH-terminal sequence of the Mtv-7 sag gene. We describe here the production of a monoclonal antibody (mAb), 3B12, which is peptide specific and reacts with a recombinant baculovirus product of Mtv-7 sag. This mAb blocks Mls-1-specific T cell recognition and detects the Mls-1 protein on the surface of the B cell hybridoma LBB.A, but not on LBB.11, which is an Mtv-7 loss variant of LBB.A. Transfection of the Mtv-7 sag gene into LBB.11 renders this cell functionally Mls-1+ as well as positive for 3B12 binding, confirming the specificity of this mAb. It is well documented that B cells and CD8+ T cells express T cell stimulatory Mls-1 determinants, and we show here that this functional profile correlates with the expression of MMTV-specific mRNA. However, primary lymphocytes derived from Mls-1+ mice do not stain with 3B12, even after in vitro activation with mitogens or phorbol ester.
Exclusion of circulating T cells from the thymus does not apply in the neonatal period.
Authors: Surh C D , Sprent J , Webb S R
Published: June 2004

Although T cells arise in the thymus, migration of mature postthymic T cells back to the thymus is very limited in adult mice and is restricted to activated cells. In neonates, by contrast, we present evidence that circulating CD4+ and CD8+ T cells with a naive/resting phenotype readily enter the thymus after intravenous injection and remain there for prolonged periods. The migration of resting T cells to the neonatal thymus is largely limited to an unusual subset of cells which lacks expression of the lymph node homing receptor, leukocyte-endothelial cell adhesion molecule 1 (LECAM-1) (MEL-14). Migration of mature T cells to the thymus in neonates may be important for self-tolerance induction.
Characterization of the T cell receptor repertoire causing collagen arthritis in mice.
Authors: Osman G E , Toda M , Kanagawa O , Hood L E
Published: June 2004

Collagen type II-induced arthritis (CIA) is generated in susceptible rodent strains by intradermal injections of homologous or heterologous native type II collagen in complete Freund's adjuvant. Symptoms of CIA are analogous to those of the human autoimmune disease, rheumatoid arthritis. CIA is a model system for T cell-mediated autoimmune disease. To study the T cell receptor (TCR) repertoire of bovine type II-specific T cells that may be involved in the pathogenesis of CIA in DBA/1Lac.J (H-2q) mice, 13 clonally distinct T cell hybridomas specific for bovine type II collagen have been established and the alpha and beta chains of their TCRs have been analyzed. These T cell hybridomas recognize epitopes that are shared by type II collagens from distinct species and not by type I collagens, and exhibit a highly restricted TCR-alpha/beta repertoire. The alpha chains of the TCRs employ three V alpha gene subfamilies (V alpha 11, V alpha 8, and V alpha 22) and four J alpha gene segments (J alpha 42, J alpha 24, J alpha 37, and J alpha 32). The V alpha 22 is a newly identified subfamily consisting of approximately four to six members, and exhibits a high degree of polymorphism among four mouse strains of distinct V alpha haplotypes. In addition, the beta chains of the TCRs employ three V beta gene subfamilies (V beta 8, V beta 1, and V beta 6), however the V beta 8.2 gene segment is preferentially utilized (58.3%). In contrast, the J beta gene segment usage is more heterogeneous. On the basis of the highly limited TCR-alpha/beta repertoire of the TCRs of the panel of bovine type II-specific T cell hybrid clones, a significant reduction (60%) of the incidence of arthritis in DBA/1Lac.J mice is accomplished by the use of anti-V beta 8.2 antibody therapy.
Downregulation of the antigen presenting cell function(s) of pulmonary dendritic cells in vivo by resident alveolar macrophages.
Authors: Holt P G , Oliver J , Bilyk N , McMenamin C , McMenamin P G , Kraal G , Thepen T
Published: June 2004

Class II major histocompatibility complex (Ia)-bearing dendritic cells (DC) from airway epithelium and lung parenchyma express low-moderate antigen presenting cell (APC) activity when freshly isolated. However, this function is markedly upregulated during overnight culture in a manner analogous to epidermal Langerhans cells. The in vitro "maturation" process is inhibited by coculture with pulmonary alveolar macrophages (PAM) across a semipermeable membrane, and the degree of inhibition achieved can be markedly increased by the presence of tumor necrosis factor alpha. In addition, PAM-mediated suppression of DC function is abrogated via inhibition of the nitric oxide synthetase pathway. Functional maturation of the DC is accompanied by increased expression of surface Ia, which is also inhibited in the presence of PAM. Prior elimination of PAM from DC donors via intratracheal administration of the cytotoxic drug dichloromethylene diphosphonate in liposomes, 24-72 h before lung DC preparation, achieves a comparable upregulation of APC activity, suggesting that (consistent with the in vitro data) the resident PAM population actively suppresses the APC function of lung DC in situ. In support of the feasibility of such a regulatory mechanism, electron microscopic examination of normal lung fixed by intravascular perfusion in the inflated state (which optimally preserves PAM in situ), revealed that the majority are preferentially localized in recesses at the alveolar septal junctions. In this position, the PAM are in intimate association with the alveolar epithelial surface, and are effectively separated by as little as 0.2 microns from underlying interstitial spaces which contain the peripheral lung DC population. A similar juxtaposition of airway intraepithelial DC is demonstrated with underlying submucosal tissue macrophages, where the separation between the two cell populations is effectively the width of the basal lamina.
Linkage of pemphigus vulgaris antibody to the major histocompatibility complex in healthy relatives of patients.
Authors: Ahmed A R , Mohimen A , Yunis E J , Mirza N M , Kumar V , Beutner E H , Alper C A
Published: June 2004

Pemphigus vulgaris (PV) is an autoimmune disease caused by high concentrations of antibody to an epidermal cadherin. The disease is associated with two kinds of HLA-DR4, DQ8 haplotypes dominantly distributed among Jewish patients, and these plus DR6, DQ5 haplotypes in non-Jewish patients. Low levels of the PV antibody were found in 48% of a total of 120 asymptomatic parents, children, and siblings of 31 patients, thus exhibiting dominant inheritance. The inheritance of these low levels of antibody in asymptomatic relatives was linked to the major histocompatibility complex with a highly significant logarithm of the odds score of 9.07, almost always to a DR4 or DR6 haplotype of the patient. Disease appears to occur in susceptible individuals with low levels of antibody when a second factor, either environmental or genetic, induces high levels, sufficient to produce blisters.
Human fetal liver gamma/delta T cells predominantly use unusual rearrangements of the T cell receptor delta and gamma loci expressed on both CD4+CD8- and CD4-CD8- gamma/delta T cells.
Authors: Wucherpfennig K W , Liao Y J , Prendergast M , Prendergast J , Hafler D A , Strominger J L
Published: June 2004

Substantial numbers of both alpha/beta and gamma/delta T cells are present in human fetal liver, which suggests a role of the fetal liver in T cell development. The diversity of fetal liver T cell receptor (TCR) gamma and delta chain rearrangements was examined among both CD4+CD8- and CD4-CD8- gamma/delta T cell clones. In addition, TCR delta chain transcripts from three fetal livers were sequenced after polymerase chain reaction amplification of TCR delta chains with V delta 1 or V delta 2 rearrangements. Five of six fetal liver gamma/delta T cell clones had a V delta 2-D delta 3-J delta 3 gene rearrangement with limited junctional diversity; three of these clones had an unusual CD4+CD8- phenotype. V delta 2-D delta 3-J delta 3 gene rearrangements were also common among both in-frame and out-of-frame transcripts from three fetal livers, indicating that they are the result of an ordered rearrangement process. TCR gamma chain sequences of the fetal liver gamma/delta T cell clones revealed V gamma 1-J gamma 2.3, V gamma 2-J gamma 1.2, and V gamma 3-J gamma 1.1 rearrangements with minimal incorporation of template-independent N region nucleotides. TCR gamma chain rearrangements found in these fetal liver T cell clones were different from those that have been observed among early thymic gamma/delta T cell populations, while similar TCR delta chain rearrangements are found among gamma/delta T cells from both sites. These data demonstrate that the fetal liver harbors gamma/delta T cell populations distinct from those found in the fetal thymus, suggesting that the fetal liver is a site of gamma/delta T cell development in humans. These unusual T cell populations may serve a specific function in the fetal immune system.