Biomedical subjects

D C Roopenian

Publications and source records attributed to D C Roopenian.

At least 55 records · Page 3Linked to original sources

PubMed1996

Frequency and histological appearance of adenomas in multiple intestinal neoplasia mice are unaffected by severe combined immunodeficiency (scid) mutation.

Well-characterized murine mutations are powerful analytical tools for the genetic analysis of tumorigenesis. We crossed the multiple intestinal neoplasia (Min) allele of adenomatous polyposis coli (Apc), which produces a profound pre-disposition to intestinal neoplasia, with the severe combined immunodeficiency (scid) mutation, which causes defective double-strand DNA repair and severe immunodeficiency, on the common C57BL/6J genetic background to assay for any combined effect on intestinal tumorigenesis. Several phenotypic traits were exacerbated in an apparently additive manner in the double mutant mice, including reduced immunoglobulin levels, reduced body weight and increased morbidity. However, quantitation and histological evaluation of polyp phenotype indicated that these mutations did not interact to affect either polyp frequency or progression. Thus, neither genome instability nor lack of immunosurveillance conferred by scid contributes to intestinal polyps in this model.

Adenomatous Polyposis Coli↗

PubMed1996

Glycosylphosphatidylinositol-anchored H-2Db molecules are defective in antigen processing and presentation to cytotoxic T lymphocytes.

Glycosylphosphatidylinositol-anchored (GPI)-Db molecules are defective in mediating cytotoxic T lymphocytes (CTL) lysis of transfected lymphoma cells, compared to their transmembrane (TM) counterpart. This defect is manifest when antigenic peptide must be processed and presented through the endogenous pathway. These same transfectants can be lysed by allospecific CTL, or by antigen-specific Db-restricted CTL when pulsed with appropriate exogenous synthetic peptide, demonstrating that they can bind and present peptide for CTL-mediated lympholysis. The defect apparently results from differences between GPI-Db and TM-Db assembly and transport, or from differences in membrane topology that affect CD8+ CTL recognition of major histocompatibility complex/peptide complex.

Animals↗

PubMed1996

Lupus nephritis in the absence of renal major histocompatibility complex class I and class II molecules.

MRL/Mp-lpr/lpr (MRL-lpr) mice develop an aggressive autoimmune disorder characterized by arthritis, vasculitis, and glomerulonephritis. Renal injury is associated with increased expression of major histocompatibility complex (MHC) molecules, as well as cytokines, adhesion molecules (intracellular adhesion molecule-1, vascular cell adhesion molecule-1), and autoantibodies. By using either MHC Class I (MRL-lpr B2m-/-) or MHC Class II deficient (MRL-lpr Ab-/-) kidneys in a transplant model, we tested the role of renal expression of these molecules in the development of autoimmune renal injury. Kidneys from MRL-lpr B2m-/- or MRL-lpr Ab-/- mice as well as control wild-type mice transplanted into MRL-lpr wt/- recipients developed nephritis, CD4+ and CD8+ T cell infiltration, and heavy glomerular deposition of immunoglobulin. Spontaneously proliferating autoreactive T cells were found in wild-type MRL-lpr and MRL-lpr B2m-/- but not MRL-lpr Ab-/- mice. These results suggest that the absence of renal expression of either Class I or Class II molecules does not provide marked protection from autoimmune lupus nephritis and supports the possibility that protection from autoimmune disease in MRL-lpr Ab-1- mice is related to the loss of autoreactive MHC Class II-dependent CD4+ T cells.

Animals↗

PubMed1996

MHC class I-mediated antigen presentation and induction of CD8+ cytotoxic T-cell responses in autoimmune diabetes-prone NOD mice.

The common class I alleles (e.g., Kd and Db) within the H2g7 major histocompatibility complex (MHC) clearly contribute to autoimmune IDDM in NOD mice, but the mechanism by which this occurs has been controversial. One laboratory has reported that the peptide transporter encoded by the Tap1 gene within H2g7 is defective, and this contributes to IDDM by impairing MHC class I-mediated antigen presentation. If true, defective MHC class I-mediated antigen presentation should segregate with the H2g7 haplotype. NOD mice, related congenic stocks, and other control strains were used to test this hypothesis. H2g7-positive strains did not differ from those expressing other MHC haplotypes in ability to present MHC class I-restricted H3aa or H3ab minor histocompatibility (H) antigens to cytotoxic T-lymphocytes (CTL). The H2g7 haplotype was found to have a reduced capacity to mediate MHC class I-restricted presentation of the H47a minor H antigen. However, MHC class I-restricted presentation of H47a was found to be Tap independent. NOD mice and control strains also did not differ in ability to activate adenovirus-specific MHC class I restricted CTL. Thus, the H2g7 haplotype is not characterized by a Tap gene defect that only impairs the inductive phase of the immune response. In addition, MHC class I-restricted presentation of either minor H or adenoviral antigens was equivalent in male and female NOD mice. Therefore, while the class I alleles of the H2g7 haplotype exert diabetogenic functions in NOD mice, this is not elicited through a Tap gene defect. The absence of female-specific Tap gene defects also indicates this cannot account for the reduced male incidence of IDDM in some NOD mouse colonies.

Alleles↗

PubMed1995

Motif-primed polymerase chain reaction-based allelotype of sarcomas induced by 3-methylcholanthrene in interspecific hybrid mice.

Loss of heterozygosity (LOH) occurs commonly in some human tumors and is thought to reflect the selective pressure exerted by tumor suppressor genes. The purpose of this study was to examine the genomic location and relative frequency of LOH of chemically induced tumors in an established mouse model for chemical carcinogenesis. Twenty-four tumors were induced by subcutaneous injection of 3-methylcholanthrene into inter-subspecific hybrid (C57BL/6J x SPRET/Ei)F1 mice. Tumors were diagnosed as poorly differentiated, spindle cell sarcomas. DNA isolated from cell cultures derived from the sarcomas was analysed for LOH using a multi-locus genome scanning technique, motif-primed PCR, followed by conventional simple sequence length polymorphism (SSLP) PCR markers. Ninety-one motif-primed PCR products and seven SSLP markers were evaluated, covering segments of 39 out of 41 chromosomes. LOH was extremely rare; average fractional allelic loss per tumor was less than 0.01 suggesting a remarkable genetic stability of the tumors and that genetic events leading to transformation are only rarely revealed as LOH. However, some regions exhibiting LOH were identified encompassing both known and hypothesized tumor suppressor loci such as Trp53. These data indicate that motif-primed PCR is an efficient method of scanning the genome of interspecific sarcomas for rare mutational events generating LOH during tumor induction. Cell lines derived from the sarcomas promise to be useful for identifying genes whose inactivation causes increased malignancy during tumor progression.

Alleles↗

PubMed1994

Transporters from H-2b, H-2d, H-2s, H-2k, and H-2g7 (NOD/Lt) haplotype translocate similar sets of peptides.

The TAP complex transports peptides from the cytosol into the lumen of the endoplasmic reticulum for presentation by major histocompatibility complex class I molecules. A limited degree of sequence polymorphism has been observed for the mouse TAP1 and TAP2 genes by restriction fragment length polymorphism and sequence analysis. However, functional polymorphism of the TAP transporter has thus far been observed for the rat only. Here we examine the effect of TAP polymorphism on ATP dependency and peptide specificity of TAP-mediated peptide transport and show that, in the mouse, polymorphism in TAP genes does not measurably alter the function of their gene products. We conclude that TAP polymorphism is unlikely to contribute to the development of autoimmune diseases and that, in the mouse, the specificity of the TAP transporter is matched to that of the F pocket of the class I molecules for which it provides the peptide substrates.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1994

Deletion mapping by immunoselection against the H-Y histocompatibility antigen further resolves the Sxra region of the mouse Y chromosome and reveals complexity of the Hya locus.

A genetic map of the mammalian Y chromosome cannot be produced by standard Mendelian methods because the Y does not participate in meiotic exchange over the majority of its length. However, deletion mapping of the mouse Y chromosome is facilitated by the fact that its short arm carries the histocompatibility-Y (Hya) locus. This locus encodes male-specific (H-Y) antigens that can be selected against in tissue culture by the technique of immunoselection. To produce cells carrying deletions, cytotoxic T lymphocytes (CTLs) specific for H-Y antigens were cocultured with a lymphoblastoid cell line derived from a mouse carrying the portion of the short arm defined by the Sxra translocation on the distal end of its X chromosome. H-Y antigen-loss variant cells that contained Y-specific deletions were identified. Molecular, karyotypic, and immunological analysis of the deletion variants allowed us to define up to 16 ordered intervals and suggested an overall organization of Sxra. The analysis also suggests that at least two and up to five distinct loci encode H-Y antigens.

Animals↗

PubMed1994

Gene mapping in a murine cell line by immunoselection with cytotoxic T lymphocytes.

Minor histocompatibility (H) loci encode alloantigens that are recognized by cytotoxic T (Tc) lymphocytes. A (C57BL/10 x 129)F1-derived transformed lymphocyte cell line was immunoselected in vitro with cloned Tc cells that were specific for H-3aa, a Chromosome 2-encoded minor H antigen. This cell line is heterozygous at H-3a (former symbol, Cd-1) and other loci. Three groups of antigen-loss variants were identified. One group contained mutations affecting only the antigen-encoding gene. Another group probably arose through a single homologous interchromosomal exchange, resulting in extensive regions of loss of heterozygosity (LOH). The third group of variants contained an interstitial LOH, one of which was shown to be a significant deletion. Several deletion boundaries were identified, one of which ordered the closely linked H-3a and beta 2-microglobulin (B2m) genes. We suggest that Tc immunoselection against minor H antigens is a promising approach for targeting negative selection to specified chromosomal regions and can provide high-resolution genetic map information.

Animals↗

PubMed1994

Oral infection with Porphyromonas gingivalis and induced alveolar bone loss in immunocompetent and severe combined immunodeficient mice.

The suitability of a mouse model for host response in the induction of alveolar bone loss by Porphyromonas gingivalis was explored. The mouths of immunocompetent and severe combined immunodeficient (SCID) mice were infected with P. gingivalis ATCC 53977. P. gingivalis was not isolated from the mouths of these mice before infection, but was present at least 42 days after infection. P. gingivalis-specific IgG was present in sera from the infected, immunocompetent mice at the end of these experiments (42 days). Specific IgG was not present in sham-infected or uninfected immunocompetent mice, nor in any immunodeficient mice. Specific IgM was not present in any sera at 42 days. Infected, immunocompetent mice of two strains showed significant bone loss in comparison to sham-infected or uninfected immunocompetent mice (p < 0.05). Infected SCID mice, which are genetically lacking both B and T lymphocytes, also showed significant bone loss compared with sham-infected or uninfected SCID mice (p < 0.05). However, the degree of bone loss was greater in immunocompetent than immunodeficient mice: the relative amount of bone in infected mice was 77% of that in sham-infected immunocompetent mice, and 86% of sham values in SCID mice (p = 0.025). Thus oral infection of mice is a feasible model for studying the effects of host response on P. gingivalis-induced alveolar bone loss. Because bone loss was induced both in immunocompetent and SCID mice but was greater in immunocompetent mice, it appears that neither B nor T cells are absolutely necessary for bone resorption in response to P. gingivalis infection but they may significantly modulate the degree of resorption.

Alveolar Bone Loss↗

PubMed1994

Major histocompatibility complex class I-deficient NOD-B2mnull mice are diabetes and insulitis resistant.

Specific allelic combinations within the class II region of the major histocompatibility complex (MHC) represent a major genetic component for susceptibility to autoimmune insulin-dependent diabetes mellitus (IDDM) in humans. We produced and used a stock of NOD/Lt mice congenic for a functionally inactivated beta 2-microglobulin (B2mnull) locus to assess whether there was an absolute requirement for MHC class I expression and/or CD8+ T-cells in diabetogenesis. These NOD-B2mnull mice do not express cell surface MHC class I molecules or produce detectable levels of CD8+ T-cells and are diabetes and insulitis resistant. Previous results from transgenic mouse models indicated that intracellular accumulation of MHC class I molecules negatively affects pancreatic beta-cell function and can result in the development of nonautoimmune insulin-dependent diabetes mellitus (IDDM). MHC class I molecules have been shown to accumulate intracellularly in the presence of a disrupted B2m locus, but this mutation does not negatively affect plasma insulin levels in either NOD/Lt mice or in those of a mixed 129 and C57BL/6 genetic background. Interestingly, 14% of the male mice in this mixed background did develop hyperinsulinemia (> 1,500 pM) independent of the disrupted B2m locus, suggesting that these mice could conceivably develop insulin-resistant diabetes. However, none of these mice became diabetic at up to 22 months of age. Thus, elimination of cell surface MHC class I expression with a disrupted B2m gene blocks autoimmune diabetes in NOD/Lt mice, without engendering a separate, distinct form of glucose intolerance.

Animals↗

PubMed1993

The functional basis of minor histocompatibility loci.

This work addresses the functional basis of classical minor histocompatibility (H) loci. We focus on the H-3 locus, which is actually a complex genetic unit to which the phenotypic trait of tissue rejection, genes whose products stimulate specific subsets of T cells, and Ir genes have been mapped. To clarify how these genes relate to one another and to the trait of tissue rejection, strains of intra-H-3 recombinant mice were produced and analyzed. These mice allowed us to selectively elicit immune responses to Ag (referred to as type I Ag) that stimulate MHC class I-restricted CTL, or Ag (referred to as type II Ag) that stimulate MHC class II-restricted Th. The splitting of H-3 in this manner resulted in a dramatic diminution of the skin allograft response, and with rare exception, an elimination of the CTL response after spleen cell immunization. A selective response to type I Ag resulted in slow, incomplete skin allograft rejection that demonstrated both CD4+ cell-dependent and -independent components. A selective response to the type II Ag failed to result in allograft rejection. The type II Ag did, however, act as an Ir gene that determined whether responses to type I Ag could occur. Altogether, the results indicate that the trait of tissue rejection associated with H-3 is a consequence of the strongly synergistic effects of Th-CTL collaboration induced by products of type I and type II genes. Moreover, the results suggest a genetic explanation for some of the Ir gene effects associated with H-3.

Animals↗

PubMed1993

Resolution of blood-stage malarial infections in CD8+ cell-deficient beta 2-m0/0 mice.

We utilized a definitive model of CD8+ T cell deficiency, the beta 2-microglobulin-deficient (beta 2-m0/0) mouse, to determine whether CD8+ T cells are required in the resolution of blood-stage malaria. In a parallel experiment, C57Bl/6 mice treated with anti-CD8 mAb showed significantly higher levels of parasitemia than untreated C57Bl/6 control mice at several points during the infection. This finding suggests some role for CD8+ cells in containing malaria. However, the beta 2-m0/0 mice, which are genetically blocked from expressing MHC class I or class Ib glycoproteins and therefore have < 2.5% of the normal number of CD8+ T cells, nevertheless resolved infections with three virulence variants of murine Plasmodium. The resolution of Plasmodium chabaudi adami, Plasmodium yoelii yoelii 17X, and Plasmodium chabaudi chabaudi AS infections by beta 2-m0/0 mice in the virtual absence of CD8+ cells demonstrates that these cells are not required to suppress murine malaria and that the suppression mechanism is not MHC class I restricted. The similarity of the time-course for resolution of infection in beta 2-m0/0 and intact control mice with all three subspecies of Plasmodium further supports the lack of a requirement for CD8+ T cells in the suppression of malarial parasitemia.

Animals↗

PubMed1993

Expansion of the CD4-, CD8- gamma delta T cell subset in the spleens of mice during non-lethal blood-stage malaria.

Splenic gamma delta T cells (CD4-, CD8-) increased more than 10-fold upon resolution of either Plasmodium chabaudi adami or P.c. chabaudi infections in C57BL/6 mice compared to controls. Similarly, a 10- to 20-fold expansion of the gamma delta T cell population was observed in beta 2-microglobulin deficient (beta 2-m0/0) mice that had resolved P.c. adami, P.c. chabaudi or P. yoelii yoelii infections. In contrast, increases in the number of splenic alpha beta T cells in these infected mice were only two to three-fold indicating a differential expansion of the gamma delta T cell subset during malaria. Because nucleated cells of beta 2-m0/0 mice lack surface expression of major histocompatibility complex class I and class Ib glycoproteins, our findings suggest that antigen presentation by these glycoproteins is not necessary for the increasing number of gamma delta T cells. Our observation that after resolution of P.c. adami malaria, C57BL/6 mice depleted of CD8+ cells by monoclonal antibody treatment had lower numbers of gamma delta T cells than untreated controls suggests that the demonstrated lack of CD8+ cells in beta 2-m0/0 mice does not contribute to the expansion of the gamma delta T cell population during non-lethal malaria.

Animals↗

PubMed1993

The genetic origin of minor histocompatibility antigens.

The purpose of this study was to elucidate the genetic origin of minor histocompatibility (H) antigens. Toward this end common inbred mouse strains, distinct subspecies, and species of the subgenus Mus were examined for expression of various minor H antigens. These antigens were encoded by the classical minor H loci H-3 and H-4 or by newly identified minor H antigens detected as a consequence of mutation. Both minor H antigens that stimulate MHC class I-restricted cytotoxic T cells (Tc) and antigens that stimulate MHC class II-restricted helper T cells (Th) were monitored. The results suggested that strains of distinct ancestry commonly express identical or cross-reactive antigens. Moreover, a correlation between the lack of expression of minor H antigens and ancestral heritage was observed. To address whether the antigens found on unrelated strains were allelic with the sensitizing minor H antigens or a consequence of antigen cross-reactivity, classical genetic segregation analysis was carried out. Even in distinct subspecies and species, the minor H antigens always mapped to the site of the appropriate minor H locus. Together the results suggest: 1) minor H antigen sequences are evolutionarily stable in that their pace of antigenic change is slow enough to predate subspeciation and speciation; 2) the minor H antigens originated in the inbred strains as a consequence of a rare polymorphism or loss mutation carried in a founder mouse stock that caused the mouse to perceive the wild-type protein as foreign; 3) there is a remarkable lack of antigenic cross-reactivity between the defined minor H antigens and other gene products.

Animals↗

PubMed1993

High-resolution mapping of a minor histocompatibility antigen gene on mouse chromosome 2.

Minor histocompatibility (H) loci are significant tissue transplantation barriers but are poorly understood at the genetic and molecular level. We describe the construction of a high-resolution genetic map that positions a class II MHC-restricted minor H antigen locus and orders 12 other genes and genetic markers within the we-un interval of mouse Chromosome (Chr) 2. An intersubspecific backcross between B10.UW/Sn-H-3b and CAST/Ei, an inbred stock of Mus musculus castaneus, was used for this purpose. A total of 1168 backcross mice were generated, and 71 we-un recombinants were identified. Significant compression of the genetic map in males versus females and transmission distortion of CAST-derived we, un, and Aw genes were observed. Monoclonal T cell lines specific for two minor H alloantigens, Hd-1a and Hd-2a, encoded by gene(s) that map to the we-un interval were used to antigen type the backcross mice. The results suggest the Hd-1a and Hd-2a antigens are most likely encoded by a single gene, now referred to as H-3b. The determined gene order is we-0.09 +/- 0.09-Itp-0.62 +/- 0.23-D2Mit77-0.26 +/- 0.15-[Evi-4, Pcna, Prn-p]-0.26 +/- 0.15-Scg-1-0.44 +/- 0.19-[Bmp2a, D2Mit70]-0.09 +/-. 0.09-[D2Mit19, D2Mit46]-1.59 +/- 0.36-D2Mit28-0.97 +/- 0.28-D2Ler1-1.50 +/- 0.35-H-3b-0.26 +/- 0.15-un (% recombination +/- 1 SE). Because the average resolution of the backcross is 0.09 cM, the backcross panel should facilitate the physical mapping and molecular identification of a number of genes in this chromosome region.

Animals↗

PubMed1992

What are minor histocompatibility loci? A new look at an old question.

In this article, Derry Roopenian relates the traditional view of minor histocompatibility (H) loci to recent advances in understanding of the tissue rejection process and the molecular nature of minor histocompatibility antigens. He proposes that minor H loci can be subdivided by the ability of their products to stimulate different T-cell subsets and discusses the implications of this concept in terms of the origins and behavior of minor H loci and their antigens, tumor immunology and autoimmunity.

Animals↗

PubMed1991

Additional mapping of mouse chromosome 2 genes.

The purpose of this work was to elucidate the genetic fine structure of the central portion of mouse chromosome (Chr) 2. Seven Chr 2 congenic mouse strains [B10.PA(L)-pa we un at, B10.PA(L)-pa Aw, B10.PA(L)-we un at, B10.PA(J)-pa a, B10.FS-we Aw, B10.C-we Aw, and B10.YBR-a] were produced. Breeding studies were carried out using strains B10.PA(L)-pa we un at and B10.LP-H-13b to accurately determine the recombination frequencies between marker genes pa and we (1.9% +/- 0.3), we and un (8.8% +/- 0.5), and un and at (4.5% +/- 0.4) of strain B10.PA(L)-pa we un at. These strains and other Chr 2 congenic strains were typed for immunologically defined loci using monoclonal antibody (mAb) C23 reactive with the gene product of B2mb T-lymphocyte clone C1 reactive with the gene product of H-3a and H-3c, and lymphocyte clone H1.8 reactive with the gene product of Hd-1a. B2m and H-3 typing located a recombinational event separating [pa B2m H-3] from we (the order of bracketed genes is not known). Hd-1 typing indicated that Hd-1 maps distal to [H-42, H-44] and proximal to un. The gene order [pa, B2m, H-3], we, [H-42, H-45], Hd-1, un, H-13, at, with H-44 mapping centromeric to Hd-1, is indicated by the data.

Animals↗

PubMed1990

Complexity at the mouse minor histocompatibility locus H-4.

The fine immunogenetics of the chromosome 7 mouse minor histocompatibility (H) locus H-4 was investigated. Both class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocytes (CTL) and class II MHC-restricted "helper" T cells (TH) specifically reactive with H-4 antigens were isolated as clones and were used as genetic probes for classical backcross segregation analysis. Results of a four point cross indicated that the H-4 locus was actually comprised of two genes, that have been designated H-46 and H-47. The former encodes antigens recognized by the TH and the latter encodes antigens recognized by the CTL. Moreover, these two genes could be separated from the gene pink-eyed dilution (p) which was found to be "sandwiched" between them. The functional significance of a minor H congenic strain differing by both TH-defined H-46 and CTL-defined H-47 was addressed using F1 complementation tests. Such studies indicated that immune responses against H-46 antigens was required for generation of H-47-specific CTL. Altogether, these results suggest selective presentation of different minor H gene products by class I or class II MHC proteins and that the minor H "locus" H-4 may have necessarily included both TH and CTL-defined genes because of requisite TH-CTL collaboration.

Animals↗