The perlecan fragment LG3 regulates homing of mesenchymal stem cells and neointima formation during vascular rejection

Transplant vasculopathy is associated with neointimal accumulation of recipient-derived mesenchymal stem cells. Increased circulating levels of LG3, a C-terminal fragment of perlecan, were found in renal transplant patients with vascular rejection. Here, we evaluated whether LG3 regulates the migration and homing of mesenchymal stem cells and the accumulation of recipient-derived neointimal cells. Mice were transplanted with a fully-MHC mismatched aortic graft followed by intravenous injection of recombinant LG3. LG3 injections increased neointimal accumulation of α-smooth muscle actin positive cells. When green fluorescent protein (GFP)-transgenic mice were used as recipients, LG3 injection favored accumulation of GFP+ cells to sites of neointima formation. LG3 increased horizontal migration and transmigration of mouse and human MSC in vitro and led to increased ERK1/2 phosphorylation. Neutralizing β1 integrin antibodies or use of mesenchymal stem cells from α2 integrin-/- mice decreased migration in response to recombinant LG3. Reduced intima-media ratios and decreased numbers of neointimal cells showing ERK1/2 phosphorylation were found in α2-/- recipients injected with recombinant LG3. Collectively, our results suggest that LG3, through interactions with α2β1 integrins on recipient-derived cells leading to activation of ERK1/2 and increased migration, favors myointimal thickening.

Primary gastric plasmacytoma: a rare cause of hypertrophic gastritis in an adolescent

BACKGROUND

This report describes a 16-year-old patient with gastric rugal hypertrophy caused by a primary gastric plasmacytoma. She had a 3-month history of nausea and burning abdominal pain. Radiographic studies showed giant rugal hypertrophy. Superficial endoscopic gastric biopsies showed mild inflammation with plasma cells of polyclonal origin in the mucosa. When symptoms persisted, she underwent laparoscopic full-thickness gastric biopsy. There was monoclonal plasma cell infiltration histologically diagnostic of plasmacytoma and inconsistent with Helicobacter pylori-associated mucosa-associated lymphoid tissue (MALT) lymphoma. There was no evidence for involvement of the bone marrow or regional lymph nodes. The tumor did not respond to radiotherapy, necessitating total gastrectomy.

METHODS

Blood samples were analyzed for interleukin (IL)-6 by enzyme-linked immunosorbent assay. Gastric biopsy and gastrectomy specimens were subjected to immunophenotyping for kappa and lambda light chains, CD45, CD20, and LN1 and to polymerase chain reaction analysis for herpes virus HHV8.

RESULTS

There was no elevation in circulating IL-6 levels, militating against a pathogenesis akin to that of Castleman's disease. There was no evidence for infection with the Kaposi's sarcoma-associated herpes virus HHV8, which has recently been found in patients with multiple myeloma.

CONCLUSIONS

This diagnosis and the characteristics of the tumor are very unusual, if not unique, for a patient of this age. The diagnostic evaluation of this patient also demonstrates the importance of deep endoscopic or full-thickness biopsies in some children with hypertrophic gastritis.

Development of leukemia in mice transgenic for the tax gene of human T-cell leukemia virus type I

The human T-cell leukemia virus type I Tax protein trans-activates several cellular genes implicated in T-cell replication and activation. To investigate its leukemogenic potential, Tax was targeted to the mature T-lymphocyte compartment in transgenic mice by using the human granzyme B promoter. These mice developed large granular lymphocytic leukemia, demonstrating that expression of Tax in the lymphocyte compartment is sufficient for the development of leukemia. Furthermore, these observations suggest that human T-cell leukemia virus infection may be involved in the development of large granular lymphocytic leukemia.

The proto-oncogene c-fgr is expressed in normal mantle zone B lymphocytes and is developmentally regulated during myelomonocytic differentiation in vivo

The proto-oncogene c-fgr is a member of the c-src gene family of cytoplasmic tyrosine kinases. Previous studies have suggested that it is normally expressed in neutrophils, monocytes, macrophages, and natural killer cells. c-fgr is also expressed in the B cells of certain lymphoproliferative disorders, namely, Epstein-Barr virus-associated lymphoproliferative disease, and in chronic lymphocytic leukemia, but it has not previously been detected in normal or reactive human lymphoid tissue. In this study we have determined the pattern of p55c-fgr protein expression in normal human hematopoietic and lymphoid tissues at the single-cell level using immunohistochemical and immunofluorescent techniques. We show that p55c-fgr expression is developmentally regulated with high-level expression first evident at the myelocyte stage of myeloid differentiation. In addition, we show that p55c-fgr is expressed in circulating B lymphocytes isolated from chronic lymphocytic leukemia patients but is not expressed in normal circulating B lymphocytes. Surprisingly, p55c-fgr is also expressed in a subpopulation of normal B lymphocytes, the mantle zone B lymphocytes. This demonstration that p55c-fgr is expressed in a normal B-lymphocyte subpopulation suggests that its expression in certain B-cell lymphoproliferative disorders may be an indirect consequence of, rather than a primary cause of, the neoplastic transformation process.

Genetic transfer and expression of reconstructed yeast artificial chromosomes containing normal and translocated BCL2 proto-oncogenes

The goal of this study was to determine whether it will be feasible to study the expression of a large, human gene, such as the BCL2 proto-oncogene, by DNA transfection. The BCL2 proto-oncogene is 230 kb in size and is deregulated in tumor cells by translocation into the immunoglobulin heavy-chain locus. Yeast artificial chromosomes (YACs) containing the human BCL2 gene were altered by homologous recombination in Saccharomyces cerevisiae to yield replicas of the normal and translocated alleles. Constructions containing either allele and ranging in size from 360 to 800 kb were integrated stably into a mouse tumor line. Fifty-eight percent of the clones contained a copy of the entire YAC insert. Over 50% of these clones expressed appropriate levels of human BCL2 RNA and protein. These studies suggested that the expression of large human genes and their pathologic rearrangements can be studied by transfection techniques employing YACs propagated in S. cerevisiae.

BCL2 protein is topographically restricted in tissues characterized by apoptotic cell death

The BCL2 protooncogene encodes an inner mitochondrial membrane protein that blocks programmed cell death. BCL2 was isolated from the chromosomal breakpoint of follicular B-cell lymphoma. Transgenic mice that overexpress BCL2 display extended survival of resting B cells. In this study we use a monospecific anti-human BCL2 antibody to define the distribution of BCL2 protein within organized tissues. BCL2 is restricted within germinal centers to the follicular mantle and to portions of the light zone implicated in the selection and maintenance of plasma cells and memory B cells. BCL2 is present in the surviving T cells in the thymic medulla. All hematopoietic lineages that derive from a renewing stem cell also display BCL2. A limited number of nonlymphoid tissues demonstrate BCL2 and can be grouped as (i) glandular epithelium in which hormones or growth factors regulate hyperplasia and involution, (ii) complex differentiating epithelium such as skin and intestine characterized by long-lived stem cells, and (iii) long-lived postmitotic cells such as neurons. Within these tissues that demonstrate apoptotic cell turnover, BCL2 is often topographically restricted to long-lived or proliferating cell zones. BCL2's function as an antidote to apoptosis may confer longevity to progenitor and effector cells in these tissues.

Immunolocalization of the Bcl-2 protein within hematopoietic neoplasms

The Bcl-2 proto-oncogene was discovered at the t(14;18) breakpoint found in most follicular B-cell lymphomas and some diffuse large-cell lymphomas. Bcl-2 is unique among proto-oncogenes, being localized to mitochondria and extending cell survival by blocking programmed cell death. We examined Bcl-2 protein expression in 82 hematologic malignancies and reactive lymphoid processes. All lymphomas with Bcl-2 rearrangement demonstrated high levels of Bcl-2 protein. However, most follicular and diffuse lymphomas without Bcl-2 rearrangement also displayed intense Bcl-2 staining. In these cases, mechanisms other than classic translocation may be deregulation Bcl-2. The pattern of Bcl-2 staining in follicular lymphoma is the inverse of the pattern in reactive hyperplasia, confirming a role for Bcl-2 immunolocalization in routine diagnosis. Small lymphocytic malignancies, including small lymphocytic lymphoma, mantle zone lymphoma, and chronic lymphocytic leukemia, expressed intermediate levels of Bcl-2. Bcl-2 protein varied in plasma cell dyscrasias. Bcl-2 protein levels in T-cell lymphomas reflected their corresponding stage of development. No substantial Bcl-2 was present in the Reed-Sternberg cells of nodular sclerosing Hodgkin's disease. Chronic myelogenous leukemia was strongly positive for Bcl-2, consistent with the presence of Bcl-2 in normal myeloid progenitors. Immunohistochemistry identified an expanded spectrum of hematopoietic neoplasms in which Bcl-2 may provide a cell survival advantage.

The t(10;14)(q24;q11) of T-cell acute lymphoblastic leukemia juxtaposes the delta T-cell receptor with TCL3, a conserved and activated locus at 10q24

We cloned the t(10;14) recurrent translocation from CD3-negative T-cell acute lymphoblastic leukemia cells. The breakpoint at 14q11 involved an intermediate rearrangement of the delta T-cell receptor locus, suggesting that the translocation arose at the time of antigen receptor assemblage. Translocation introduced chromosome segment 10q24 as proven by hybridization of a breakpoint-derived probe to flow-sorted chromosomes and metaphase chromosomes. Two t(10;14) breakpoints were clustered within a 600-base-pair region of 10q24 but no heptamer-spacer-nonamer motifs resembling T-cell receptor/immunoglobulin rearrangement signals were noted at the breakpoint. A locus distinct from terminal deoxynucleotidyltransferase was found at 10q24. Evolutionarily conserved regions surrounding the 10q24 breakpoint were examined for transcriptional activity. A region telomeric to the 10q24 breakpoint, expected to translocate to the der(14) chromosome, recognized an abundant 2.9-kilobase RNA in a t(10;14) T-cell leukemia. This locus was not active in a variety of other normal and neoplastic T cells, arguing that it was deregulated by the introduction of the T-cell receptor. This locus is a candidate for a putative protooncogene, TCL3, involved in T-cell neoplasia.

Oligoclonal immunoglobulin heavy chain gene rearrangement in a childhood immunoblastic lymphoma. Presentation as a polyphenotypic atypical lymphoproliferative reaction

The authors describe a diagnostically difficult case of childhood lymphoma that presented as an atypical polyphenotypic lymphoproliferative reaction. Initial immunophenotyping revealed the presence of IgG, IgA, kappa, and lambda within the neoplastic lymphocytes. The patient had circulating plasmacytoid lymphocytes and a polyclonal hypergammaglobulinemia. The patient died of widespread immunoblastic lymphoma in two months. Postmortem tumor DNA showed a oligoclonal pattern of immunoglobulin heavy chain gene rearrangement. Blots for T-cell receptor beta-chain rearrangement showed germline bands. Epstein-Barr virus DNA was present within tumor cells, but there was no history of prior immunosuppression or serologic evidence of Epstein-Barr virus infection. The apparent polyclonal nature of the immunoproliferation delayed the institution of chemotherapy.

Treatment of acute graft-versus-host disease with anti-CD3 monoclonal antibodies

A dose-escalation trial was carried out to determine the efficacy and safety of using an IgG2a anti-CD3 monoclonal antibody to treat acute graft-v-host disease (GVHD) in marrow transplant recipients. Two patients received the antibody as the initial treatment of GVHD, and 22 patients received the antibody after failure of initial treatment with corticosteroids, cyclosporine, antithymocyte globulin (ATG), or combined ATG and cyclosporine. Antibody was administered at four dose levels, beginning at approximately 0.015 mg/kg/d and increasing by threefold increments. The initial doses of antibody were nearly always associated with fever and chills, and treatment had to be discontinued in one patient because of intolerable side effects. Improvement in skin disease could be reliably achieved at a dose of 0.15 mg/kg/d, but threefold higher doses appeared to be necessary for improvement in the liver or gut. In no case was there complete resolution of all manifestations of disease, and all patients surviving after antibody treatment required additional immunosuppressive treatment. Four patients developed Epstein-Barr virus (EBV)-associated lymphoproliferative disorders within seven to 18 days after starting antibody therapy. The overall risk of this complication in patients not given anti-CD3 monoclonal antibody is less than 1%. Anti-CD3 antibody represents an effective immunosuppressive agent for treatment of acute GVHD, but this treatment is associated with a substantial risk of EBV-associated lymphoproliferative disorders.

Flow dependence of the intrapulmonary distribution of inspired boluses of 133 Xe in smokers and non-smokers

1. Starting at 50% vital capacity, boluses of 133Xe were inhaled either at very low or maximal flow rates, the inspiration terminating at total lung capacity (TLC). Flow-dependent changes in bolus distribution were examined by measuring regional radioctivity and computing regional time-constants, and also by recording alveolar plateaux during the subsequent vital capacity expiration. Regional residual volumes, as a fraction of regional total lung capacities, were also calculated. Three groups of subjects were studied: young non-smokers, young cigarette smokers, and older non-smokers.

2. All three groups gave similar results in terms of regional time-constants though there was less variation in the results for young non-smokers.

3. Regional residual volumes also gave similar results in all groups although again there was less variation in young non-smokers. In young smokers, residual volumes in some regions depended on the flow rate used in their measurement, which indicated intraregional inhomogeneity of function.

4. In young non-smokers alveolar plateaux after slow and fast bolus inspirations differed little; this was not the case either in older subjects or in smokers. The increased flow-dependence of the alveolar plateau is analogous with the increased frequency-dependence of dynamic compliance and probably indicates obstruction of small peripheral airways.