PubMed Health⌕ Search

Biomedical subjects

M A Duchosal

Publications and source records attributed to M A Duchosal.

At least 19 recordsLinked to original sources
PubMed1998

hu-PBL-SCID mice: an in vivo model of Epstein-Barr virus-dependent lymphoproliferative disease.

The Epstein-Barr virus (EBV) exists in most humans as a lifelong latent infection established in host B cells after a primary viral encounter. In immunosuppressed individuals, such as post-transplant patients, the presence of EBV-infected B cells may lead to lymphoproliferative disease. Injection of human peripheral blood lymphocytes from EBV-positive donors into mice with severe combined immunodeficiency induces human lymphoproliferative disease in the recipient closely resembling that of human post-transplant patients. This xenochimeric human-mouse model is increasingly being used to elucidate the mechanisms of EBV-specific lymphomagenesis and to assess novel therapeutic approaches.

Animals↗
PubMed1997

B-cell development and differentiation.

B-cell development is characterized by antigen-independent phases in fetal hematopoietic organs and adult bone marrow, which lead to naive recirculating B cells in the periphery. The diversity of the naive (primary) B-cell repertoire resides in somatic events where minigenes from a large available repertoire are imprecisely rearranged and encode antigen-binding sites of antibodies. Naive B cells expand upon antigenic stimulation, acquire somatic mutations leading to high-affinity antibodies, and switch immunoglobulin (Ig) isotype in peripheral lymphoid organs. This immune reaction leads to the generation of memory B cells, which are long-lived and capable of rapid generation of specific high-affinity antibodies upon recall antigenic stimulation, as well as plasma cells, which constitutively secrete a large amount of antibodies.

Antigens, Differentiation↗
PubMed1996

In vivo immunosuppression by targeting a novel protease receptor.

Membrane receptors for blood proteases govern the clotting and fibrinolytic cascades, regulate signal transduction and control the growth of mesenchymal cells. Despite their importance in the development of vascular injury, it is unclear whether these mechanisms participate in the generation of an immune response. Here we report that targeting a factor Xa receptor, designated effector cell protease receptor-1 (EPR-1), with antisense oligonucleotide or with a monoclonal antibody (mAB 2E1) inhibited CD3/T-cell receptor-dependent lymphocyte proliferation. Immunosuppression was mediated by abolishing cytokine production and down-modulating membrane expression of the interleukin (IL)-2 receptor. In vivo administration of mAb 2E1 to severe-combined-immunodeficient mice injected with human peripheral blood leukocytes suppressed production of human immunoglobulin, abolished graft-versus-host disease, and protected these xenochimaeric mice from Epstein-Barr-virus-induced human lymphoproliferative disease. These observations indicate a new role for protease receptors in the regulation of the immune response, and identify a potential target for therapeutic immunosuppression in humans.

Animals↗
PubMed1996

Human immunoglobulins produced in hu-PBL-SCID mice are polyclonal early after xenotransplantation.

Xenotransplantation of human peripheral blood leukocytes (hu-PBL) to severe combined immune-deficient (SCID, hu-PBL-SCID) mice leads to human immunoglobulin (Ig) production in the animals. Here we used a sensitive high-resolution two-dimensional electrophoresis (2D-PAGE) technique to separate, and to analyze, Ig gamma and light chains in sera from SCID mice given hu-PBL for less than 35 days. Human Igs in the model appeared polyclonal until 3 weeks after cell transfer. After this period, oligoclonal Igs progressively replaced this polyclonal background. The 2D-PAGE pattern evolution of human Igs was similar when hu-PBL originated from donors with or without previous contact with the Epstein-Barr virus. The broad diversity of human Igs, and therefore the large expressed B cell repertoire, in hu-PBL-SCID mice during a period that allows manipulation (such as immunization) of the human graft has evident implication for the use of this model in the generation of specific antibodies of desired specificity.

Animals↗
PubMed1993

Circulating soluble CR1 (CD35). Serum levels in diseases and evidence for its release by human leukocytes.

C receptor type 1 (CR1, CD35) is present in a soluble form in plasma (sCR1). Soluble CR1 was measured with a specific ELISA assay in normal individuals and in patients with different diseases. The mean serum concentration of sCR1 in 31 normal donors was 31.4 +/- 7.8 ng/ml, and was identical in plasma. An increase in sCR1 was observed in 36 patients with end-stage renal failure on dialysis (54.8 +/- 11.7 ng/ml, p < 0.0001), and in 22 patients with liver cirrhosis (158.3 +/- 49.9 ng/ml, p < 0.0001). The mean sCR1 levels dropped from 181 +/- 62.7 to 52.1 +/- 24.0 ng/ml (p < 0.001) in nine patients who underwent liver transplantation, and was 33.5 +/- 7.3 in 10 patients with functioning renal grafts, indicating that the increase in sCR1 was reversible. Soluble CR1 was elevated in some hematologic malignancies (> 47 ng/ml), which included B cell lymphoma (12/19 patients), Hodgkin's lymphoma (4/4), and chronic myeloproliferative syndromes (4/5). By contrast, no increase was observed in acute myeloid or lymphoblastic leukemia (10) or myeloma (5). In two patients with chronic myeloproliferative syndromes, sCR1 decreased rapidly after chemotherapy. The mean concentration of sCR1 was not significantly modified in 181 HIV-infected patients at various stages of the disease (34.8 +/- 14.4 ng/ml), and in 13 patients with active SLE (38.3 +/- 19.6 ng/ml), although in both groups the number of CR1 was diminished on E. There was a weak but significant correlation between sCR1 and CR1 per E in HIV infection and SLE (r = 0.39, p < 0.0001, and r = 0.60, p < 0.03 respectively). In vitro, monocytes, lymphocytes, and neutrophils were found to release sCR1 into culture supernatants. In vivo, sCR1 was detected in the serum of SCID mice populated with human peripheral blood leukocytes. The sCR1 levels correlated with those of human IgG (r = 0.97, p < 0.0001), suggesting synthesis of sCR1 by the transferred lymphocytes. The mechanisms underlining the increased levels of sCR1 and its biologic consequences remain to be defined.

Animals↗
PubMed1993

Two-dimensional electrophoresis as an aid in the analysis of the clonality of immunoglobulins.

In this paper, we summarize our five-year observation of two-dimensional polyacrylamide gel electrophoretic (2-D PAGE) analysis of immunoglobulin (Ig) light (L) chain patterns on serum/plasma and/or purified human Ig, and compare this technique with agarose electrophoresis and/or immunofixation examination. Polyclonal Ig L chains were seen as large "fuzzy" areas with several zones of high density. The majority (71%) of the monoclonal Ig L chains of monoclonal gammopathy detected by conventional electrophoresis appeared as a single large and well-defined spot on 2-D PAGE analysis, with the remaining appearing as multiple spots. The presence of oligoclonal Ig, reflected by multiple spots in 2-D PAGE, and several bands in immunofixation, was observed in 5 of 26 patients after allogeneic bone marrow transplantation and in 5 patients with tumors. In the majority (77%) of hypergammaglobulinemia, L chains appeared as a wide spread of small and well-defined spots in 2-D PAGE analysis. This pattern suggested oligoclonal Ig-secreting B cell clone expansion, and corresponding abnormalities were not detected with immunofixation. 2-D PAGE analysis also detected oligoclonal Ig expansions whereas conventional electrophoretic examination was normal in 10 additional patients after bone marrow transplantation, and in 6 of 10 immunocompetent patients with acute severe infections. Analysis of the Ig L chain pattern of a severe combined immune-deficient mouse populated with human peripheral blood leukocytes confirmed the skewed human Ig production in the model. In summary, 2-D PAGE appears to be a sensitive tool for the analysis of Ig diversity in various clinical situations.

Animals↗
PubMed1992

Immunization of hu-PBL-SCID mice and the rescue of human monoclonal Fab fragments through combinatorial libraries.

Antibodies are usually prepared from recently boosted animals and reflect ongoing immune responses. In humans, this is restrictive as ethical constraints generally prevent antigen-boosting. Therefore the rich memory compartment of human antibody responses remains largely untapped. Severe combined immune deficiency (SCID) mice populated with human cells allow the stimulation of human antibody memory without the usual constraints. Here we show how peripheral blood lymphocytes can be stimulated by antigen to produce large secondary responses after transfer to SCID mice. Specific monoclonal human Fab fragments can then be isolated from the mice by repertoire cloning even when the human donor's last contact with antigen was more than 17 years ago.

Amino Acid Sequence↗
PubMed1992

The hu-PBL-SCID mouse model. Long-term human serologic evolution associated with the xenogeneic transfer of human peripheral blood leukocytes into SCID mice.

We present a 2-year serologic analysis of severe combined immune deficiency (SCID) mice populated with human peripheral blood leukocytes (PBL, hu-PBL-SCID mice). After 10-20 x 10(6) PBL transfer, human IgG serum levels generally increased in the SCID mouse recipient for 2 months, and thereafter decreased without returning to zero for at least 2 years. Great variability existed between different hu-PBL-SCID mice with regard to Ig serum levels even when derived from the same donor's PBL aliquot. The ratio of IgM to IgG serum levels was lower in hu-PBL-SCID mice than in the donors. The half-life of human IgG in the SCID mouse is shorter than in the human (8 days vs 23 days), suggesting a much higher production of IgG than expected from serum levels. The majority of hu-PBL-SCID mouse sera analyzed by high resolution electrophoresis had a smear appearance suggestive of diverse human Ig, generally with superimposed multiple faint mIg. Few mice developed strong human mIg, associated with lymphoproliferative diseases. In the hu-PBL-SCID mouse model, the transfer of cells from donors making antibody with defined specificity against TT and nuclear antigen resulted in the appearance of these antibodies in only a minority of the recipients.

Animals↗
PubMed1992

Characterization of hu-PBL-SCID mice with high human immunoglobulin serum levels and graft-versus-host disease.

A chimeric model consisting of severe combined immune deficiency (SCID) mice populated with human peripheral blood leukocytes (PBL) has recently been described (bu-PBL-SCID mice). These reports indicated a limited reconstruction of the transferred human immune system and functionality of the human graft. Herein we described modifications of the PBL transfer method that minimize transfer time and cellular manipulations, leading to a more effective population of SCID mouse recipients. Severe combined immune deficiency mice given 15 x 10(6) PBL had human IgG serum levels reaching 2 to 5 g/l, and all mice had detectable human anti-tetanus toxoid antibody levels when they received cells from donors with such levels. These transfers were associated also with clinical and histologic evidence of graft-versus-host disease, suggesting responsiveness of the human graft in the recipients. When Epstein-Barr virus seropositive (EBV+) donors were used, the chimeric mice also showed a high incidence of fatal lymphoproliferative disease 1 to 3 months after transfer of 15 x 10(6) PBL. The high level of immunoglobulin synthesis and immunoresponsiveness of the human cells with this transfer procedure may expand the use of these chimeric mice for the manipulations of human immune cells in vivo.

Animals↗
PubMed1991

An autosomal recessive gene that delays expression of lupus in BXSB mice.

We report the generation and serologic, cellular, histologic, and genetic characteristics of a BXSB/MpJScr substrain, termed BXSB/MpJScr-ll/ll, that has lost early-life male lupus disease. Classic genetic analysis suggested that delayed disease expression results from the action of a single autosomal recessive gene. This putative gene, referred to as ll (long-lived), causes a significant delay in expression of autoimmune serology (total serum IgG and anti-nuclear antibodies levels), monocytosis, and of immune complex-mediated histopathologic changes such as glomerulonephritis, arteritis, and myocardial infarction. Presumably as a consequence of the delayed immunopathology male BXSB/MpJScr-ll/ll mice live three to four times longer than regular BXSB/MpJScr. This strain might be useful for analysis of single genes responsible for severe autoimmune disease expression.

Animals↗
PubMed1990

Transfer of human systemic lupus erythematosus in severe combined immunodeficient (SCID) mice.

To study the role of peripheral blood leukocytes (PBL) in the pathogenesis of human systemic lupus erythematosus (SLE), we transferred PBL from 5 SLE patients into 15 severe combined immunodeficiency (SCID) mice. Such reconstituted mice showed long-term presence of auto-antibodies characteristic of the donor in their sera, as well as human immunoglobulin deposition, and in some cases mouse C3, in the renal glomeruli. SCID mice repopulated with PBLs from normal donors do not develop serologic abnormalities or immunodeposits. It is concluded that human SLE serology and some associated renal changes can be reproduced solely by PBL transferred from afflicted patients, and that SCID-human-SLE mice may serve as an in vivo laboratory model for the study of human SLE.

Animals↗
PubMed1989

Autoimmune syndrome after induction of neonatal tolerance to alloantigens. CD4+ T cells from the tolerant host activate autoreactive F1 B cells.

The induction of transplantation tolerance to H-2b alloantigens in BALB/c (H-2d) mice by neonatal injection of (C57BL/6 x BALB/c)F1 spleen cells, produces an autoimmune lupus-like syndrome due to an activation of persisting F1 donor B cells. This syndrome is characterized by hypergammaglobulinaemia, high levels of anti-DNA antibodies, as well as by circulating immune complexes and glomerular deposits of Ig. The role of host T cells in this model was investigated by using athymic BALB/c nu/nu mice as recipients of normal (C57BL/6 x BALB.Igb)F1 spleen cells. In these "tolerized" BALB/c nu/nu mice, there was a persistence of F1 donor B cells but none of the autoimmune features were expressed, conversely to tolerized BALB/c nu/+ littermates. The injection of CD4+CD8- T lymphocytes from adult normal BALB/c mice in 3-wk-old tolerized BALB/c nu/nu mice triggered the appearance of all the autoimmune findings observed in euthymic tolerant mice. The autoantibodies were produced by persisting F1 donor B cells as shown by allotype analysis. More strikingly, a similar triggering of the autoimmune syndrome, including high titers of anti-DNA IgG antibodies and circulating immune complexes, was observed after injection of CD4+CD8- T cells from 2-wk-old tolerant BALB/c mice into "tolerized" BALB/c nu/nu mice. The anti-ssDNA antibodies were shown to bear only the Ighb allotype, indicating their exclusive origin from F1 donor B cells. These results imply that CD4+ T cells from the tolerant mice are necessary for the activation of autoreactive F1 B cells and for the development of the autoimmune syndrome occurring in this model. They also suggest that, although there is a marked depletion of H-2b-specific alloreactive CTL precursors in those neonatally tolerized mice, this state of tolerance can be associated with the persistence of H-2b-specific alloreactive CD4+ cells.

Animals↗
PubMed1989

Genetic diversity of murine rheumatoid factors.

Anti-Ig autoantibodies (rheumatoid factors, RF) have been implicated in the pathogenesis of human and murine rheumatoid arthritis as well as in the regulation of normal immune responses. Their genetic origin, clonal diversity, and inducing agents, and the relatedness between RF associated with disease and those occurring under physiologic conditions are not well understood. In this study, the genetic and clonotypic origin of 34 monoclonal IgM RF-secreting hybridomas from arthritic MRL-lpr/lpr and nonarthritic MRL-+/+ and C57BL/6-lpr/lpr mice was examined by RNA hybridization. For this purpose, we used probes for 10 VH and 13 Vk gene families as well as all JH and Jk gene segments. The majority of hybridomas expressed distinct Ig gene segment patterns and, hence, were clonally unrelated. Overall, a variety of different V and J gene segments were expressed in the hybridoma panel, suggesting that a large number of distinct genetic elements participates in expression of RF-like activity. RF from arthritic mice expressed Vk messages from the overlapping Vk22 and Vk28 gene families more frequently than did those from nonarthritic mice. RF from autoimmune MRL mice, both arthritic MRL-lpr/lpr and nonarthritic MRL-+/+, showed skewed JH4 segment usage, whereas those from C57BL/6-lpr/lpr preferentially expressed JH2.

Animals↗
PubMed1989

Complexity, polymorphism, and connectivity of mouse Vk gene families.

To define the polymorphism and extent of the mouse immunoglobulin kappa (Igk) gene complex, we have analyzed restriction-enzyme digested genomic DNA from 33 inbred strains of mice with labeled DNA probes corresponding to 16 Vk protein groups (1 of them previously undescribed) and the Jk/Ck region (V, variable; J, joining; C, constant). These probes detected between 1 and 25 distinct restriction enzyme fragments (REF) that appeared in up to eight polymorphic patterns, thus defining eight mouse Igk haplotypes. The investigated portion of the Vk repertoire was estimated to encompass between 60 and 120 discernable Vk gene-containing REFs. In contrast to mouse VH gene families, several Vk gene families defined by these probes appeared to overlap. This observation has implications for Vk gene analyses by nucleic acid hybridization and raises the possibility that the Vk gene complex is a continuum of related sequences.

Amino Acid Sequence↗
PubMed1988

Immunoglobulin kappa light chain variable region gene complex organization and immunoglobulin genes encoding anti-DNA autoantibodies in lupus mice.

We have investigated the genetic origin of autoantibody production in several strains of mice that spontaneously develop a systemic lupus erythematosus-like disease. Restriction fragment length polymorphism analyses of gene loci encoding kappa light chain variable regions (Igk-V) demonstrated, as shown previously for the Ig heavy chain locus, that autoantibody production and disease occur in different Igk-V haplotypes. Moreover, autoimmune mice with known genetic derivation inherited their Igk-V loci essentially unaltered from their nonautoimmune ancestors. New Zealand black lupus mice, with unknown genetic derivation, had a possibly recombinant Igk-V haplotype, composed of V kappa loci that were primarily indistinguishable from those of nonautoimmune strains from either of the two potential donor haplotypes. The heavy and light chain gene segments (variable, diversity, joining) encoding anti-DNA antibodies were diverse and often closely related, or even identical, to those found in antibodies to foreign antigens in normal mice. Only 1 of 11 sequenced variable region genes could not be assigned to existing variable region gene families; however, corresponding germline genes were present in the genome of normal mice as well. These data argue against abnormalities in the genes and mechanisms generating antibody diversity in lupus mice and suggest a remarkable genetic and structural diversity in the generation of anti-DNA binding sites.

Amino Acid Sequence↗
PubMed1987

Specificity and molecular characteristics of monoclonal IgM rheumatoid factors from arthritic and non-arthritic mice.

Two-hundred twenty-four hybridomas secreting monoclonal IgM rheumatoid factor (hIgMRF) derived from MRL-lpr/lpr, MRL-+/+ and C57BL/6-lpr/lpr autoimmune mice were analyzed with regard to IgG subclass and domain specificity, and some for VH gene expression patterns. Among these mice, only MRL-lpr/lpr develop arthritis. Clonotypes specific for each of the four mouse IgG subclasses and clonotypes reacting with more than one IgG subclass were identified. Although each panel contained several clonotypes, the predominant one differed in each strain (MRL-lpr/lpr, anti-IgG2a; MRL-+/+, combined anti-IgG2a and 2b; C57BL/6-lpr/lpr, anti-IgG1 or combined anti-IgG1, 2a, and 3). The IgG domains recognized by these monoclonals were defined with mutant Ig carrying IgG1 heavy chains that lacked either the CH1 or CH3 domains, variant Ig carrying hybrid IgG2b-2a heavy chains, and IgG fragments. Inhibition of hIgMRF binding to IgG substrates by protein A was also assessed. Most determinants were assigned to the CH3 domain, but determinants in the hinge region, CH2 domain, and in some instances, even in the Fab portion, could also be identified. Hybridization of cytoplasmic RNA from 35 classes of diverse IgG subclass specificity with VH gene probes representing seven of the approximately 10 VH families (7183, S107, Q52, J558, J606, 36-60, X24) indicated that approximately 90% of these clones expressed VH genes belonging to the large J558 gene family. The results indicate that murine IgMRF are extremely heterogeneous in IgG subclass and domain specificities; the genetic background influences RF specificity characteristics that may relate to pathogenicity; and considering the complexity of the J558 VH gene family and reported RF heavy chain assignments to additional VH gene families, it appears that VH genes encoding RF are diverse.

Animals↗