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Biomedical subjects

R Warnke

Publications and source records attributed to R Warnke.

At least 19 recordsLinked to original sources
PubMed2002

BCL-6 mRNA expression in higher grade transformation of follicle center lymphoma: correlation with somatic mutations in the 5' regulatory region of the BCL-6 gene.

Follicle center lymphoma (FCL) is an indolent low-grade B cell non-Hodgkin's lymphoma (NHL) that frequently transforms to aggressive diffuse large B cell lymphoma (DLBCL). Histological transformation of FCL is commonly associated with accumulation of secondary genetic alterations. The BCL-6 gene is commonly implicated in the pathogenesis of DLBCL and its expression may be altered by clonal rearrangements and somatic point mutations in its 5' non-translated regulatory region. Recently, somatic mutations of the BCL-6 gene were associated with the transformation process. Here, we examined BCL-6 mRNA expression and BCL-6 mutations in paired biopsies from the same patients obtained at the time of FCL diagnosis and after transformation. BCL-6 mRNA expression markedly increased upon transformation (1.9- to 4.8-fold) in three cases, remained unchanged in one case and decreased compared to the diagnosis FCL specimens in four cases. The three specimens that demonstrated an increase in the BCL-6 mRNA expression upon transformation harbored BCL-6 gene mutations in the 5' region of the first intron that overlapped with the previously reported negative regulatory region of the gene. Accumulation of new mutations in this region was not observed in DLBCL biopsies in which the BCL-6 mRNA expression did not increase. The present study demonstrates that although BCL-6 gene mutations do accumulate during the transformation process and, depending on their location within the first intron, may deregulate BCL-6 mRNA expression, increase in BCL-6 mRNA expression is not uniformly required for transformation from FCL to DLBCL.

5' Untranslated Regions↗
PubMed2001

Expression of a single gene, BCL-6, strongly predicts survival in patients with diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is characterized by a marked degree of morphologic and clinical heterogeneity. Establishment of parameters that can predict outcome could help to identify patients who may benefit from risk-adjusted therapies. BCL-6 is a proto-oncogene commonly implicated in DLBCL pathogenesis. A real-time reverse transcription-polymerase chain reaction assay was established for accurate and reproducible determination of BCL-6 mRNA expression. The method was applied to evaluate the prognostic significance of BCL-6 expression in DLBCL. BCL-6 mRNA expression was assessed in tumor specimens obtained at the time of diagnosis from 22 patients with primary DLBCL. All patients were subsequently treated with anthracycline-based chemotherapy regimens. These patients could be divided into 2 DLBCL subgroups, one with high BCL-6 gene expression whose median overall survival (OS) time was 171 months and the other with low BCL-6 gene expression whose median OS was 24 months (P =.007). BCL-6 gene expression also predicted OS in an independent validation set of 39 patients with primary DLBCL (P =.01). BCL-6 protein expression, assessed by immunohistochemistry, also predicted longer OS in patients with DLBCL. BCL-6 gene expression was an independent survival predicting factor in multivariate analysis together with the elements of the International Prognostic Index (IPI) (P =.038). By contrast, the aggregate IPI score did not add further prognostic information to the patients' stratification by BCL-6 gene expression. High BCL-6 mRNA expression should be considered a new favorable prognostic factor in DLBCL and should be used in the stratification and the design of risk-adjusted therapies for patients with DLBCL. (Blood. 2001;98:945-951)

Adolescent↗
PubMed2001

The Hox cofactor and proto-oncogene Pbx1 is required for maintenance of definitive hematopoiesis in the fetal liver.

Pbx1 is the product of a proto-oncogene originally discovered at the site of chromosomal translocations in acute leukemias. It binds DNA as a complex with a broad subset of homeodomain proteins, but its contributions to hematopoiesis have not been established. This paper reports that Pbx1 is expressed in hematopoietic progenitors during murine embryonic development and that its absence results in severe anemia and embryonic lethality at embryonic day 15 (E15) or E16. Definitive myeloerythroid lineages are present in Pbx1(-/-) fetal livers, but the total numbers of colony-forming cells are substantially reduced. Fetal liver hypoplasia reflects quantitative as well as qualitative defects in the most primitive multilineage progenitors and their lineage-restricted progeny. Hematopoietic stem cells from Pbx1(-/-) embryos have reduced colony-forming activity and are unable to establish multilineage hematopoiesis in competitive reconstitution experiments. Common myeloid progenitors (CMPs), the earliest known myeloerythroid-restricted progenitors, are markedly depleted in Pbx1(-/-) embryos at E14 and display clonogenic defects in erythroid colony formation. Comparative cell-cycle indexes suggest that these defects result largely from insufficient proliferation. Megakaryocyte- and erythrocyte-committed progenitors are also reduced in number and show decreased erythroid colony-forming potential. Taken together, these data indicate that Pbx1 is essential for the function of hematopoietic progenitors with erythropoietic potential and that its loss creates a proliferative constriction at the level of the CMP. Thus, Pbx1 is required for the maintenance, but not the initiation, of definitive hematopoiesis and contributes to the mitotic amplifications of progenitor subsets through which mature erythrocytes are generated. (Blood. 2001;98:618-626)

Anemia↗
PubMed2001

Expression of Pbx1b during mammalian organogenesis.

Mammalian Pbx genes (Pbx1-3) encode a family of TALE homeodomain proteins that function as transcriptional regulators in numerous cell types (Curr. Opin. Genet. Dev. 8 (1998) 423). The present study highlights distinctive features of Pbx1b expression during mouse embryonic development as a framework to understand its biological functions. Immunohistochemical analyses demonstrate extensive expression of Pbx1b throughout post-implantation development, with highest levels observed during early to mid-gestation. Its initial distribution is predominantly associated with condensing mesoderm, however, Pbx1b displays dynamic expression patterns in derivatives of all principal germ layers. In particular, Pbx1b localizes to sites of mesenchymal-epithelial interactions during periods of active morphogenesis in tissues such as the lung, kidney, tooth buds and vibrissae follicles. Furthermore, BrdU labeling studies reveal that Pbx1b expression domains partially overlap with regions of cellular proliferation. Taken together, these data suggest that Pbx1b contributes to multiple cellular processes during embryogenesis, which may include roles in cell-autonomous regulation as well as in the mediation of tissue interactions.

Animals↗
PubMed2000

Molecular analysis of immunoglobulin genes in diffuse large B-cell lymphomas.

Diffuse large B-cell lymphoma (DLBCL) is a common type of non-Hodgkin's lymphoma (NHL) that is highly heterogeneous from both clinical and histopathologic viewpoints. The immunoglobulin (Ig) heavy (H) chain variable region genes were examined in 71 patients with untreated primary DLBCL. Fifty-eight potentially functional V(H) genes were detected in 53 DLBCL cases; V(H) genes were nonfunctional in 9 cases and were not detected in an additional 9 cases. The use of V(H) gene families by DLBCL tumors was unbiased without overrepresentation of any particular V(H) gene or gene family. Analysis of Ig mutations in comparison to the most closely related germline gene disclosed mutated V(H) genes in all but 1 DLBCL case. More than 2% difference from the most similar germline sequence was detected in 52 potentially functional and the 8 nonfunctional V(H) gene sequences, whereas less than 2% difference from the germline sequence was observed in 3 V(H) gene isolates. Only 3 V(H) gene isolates were unmutated. No correlation was found between V(H) gene use, mutation level, and International Prognostic Index (IPI) or survival. Six of 8 tested tumors showed evidence of ongoing somatic mutations. Evidence for positive or negative antigen selection pressure was observed in 65% of mutated DLBCL cases. Our findings indicate that the etiology and the driving forces for clonal expansion are heterogeneous, which may explain the well-known clinical and pathologic heterogeneity of DLBCL. (Blood. 2000;95:1797-1803)

B-Lymphocytes↗
PubMed2000

Distinct types of diffuse large B-cell lymphoma identified by gene expression profiling.

Diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin's lymphoma, is clinically heterogeneous: 40% of patients respond well to current therapy and have prolonged survival, whereas the remainder succumb to the disease. We proposed that this variability in natural history reflects unrecognized molecular heterogeneity in the tumours. Using DNA microarrays, we have conducted a systematic characterization of gene expression in B-cell malignancies. Here we show that there is diversity in gene expression among the tumours of DLBCL patients, apparently reflecting the variation in tumour proliferation rate, host response and differentiation state of the tumour. We identified two molecularly distinct forms of DLBCL which had gene expression patterns indicative of different stages of B-cell differentiation. One type expressed genes characteristic of germinal centre B cells ('germinal centre B-like DLBCL'); the second type expressed genes normally induced during in vitro activation of peripheral blood B cells ('activated B-like DLBCL'). Patients with germinal centre B-like DLBCL had a significantly better overall survival than those with activated B-like DLBCL. The molecular classification of tumours on the basis of gene expression can thus identify previously undetected and clinically significant subtypes of cancer.

Adult↗
PubMed2000

Spontaneously relapsing clonal, mucosal cytotoxic T-cell lymphoproliferative disorder: case report and review of the literature.

Primary T-cell lymphoma of the gastrointestinal tract is a rare and usually aggressive disorder that may be associated with celiac disease. The authors describe a unique case of a clonal proliferation of CD8+ T cells involving the oral mucosa, ileum, and colon of a 35-year-old man that has regressed spontaneously and recurred numerous times over a 9-year period without treatment. The patient's symptoms were limited to occasional rectal bleeding and recurring painful oral ulcers. Within the intestine, these collections of small T cells induced minimal architectural distortions and did not show extensive epitheliotrophism. Polymerase chain reaction and sequencing analyses revealed that the identical T-cell clone has been present for more than 9 years and in different mucosal locations in this patient. This may represent a unique T-cell lymphoproliferative process akin to a mucosal counterpart of lymphomatoid papulosis of the skin.

Adult↗
PubMed1999

The chemokine receptor CCR4 in vascular recognition by cutaneous but not intestinal memory T cells.

Lymphocytes that are responsible for regional (tissue-specific) immunity home from the blood to the intestines, inflamed skin or other sites through a multistep process involving recognition of vascular endothelial cells and extravasation. Chemoattractant cytokine molecules known as chemokines regulate this lymphocyte traffic, in part by triggering arrest (stopping) of lymphocytes rolling on endothelium. Here we show that many systemic memory T cells in blood carry the chemokine receptor CCR4 and therefore respond to its ligands, the chemokines TARC and MDC. These cells include essentially all skin-homing cells expressing the cutaneous lymphocyte antigen and a subset of other systemic memory lymphocytes; however, intestinal (alpha4beta7+) memory and naive T cells respond poorly. Immunohistochemistry reveals anti-TARC reactivity of venules and infiltration of many CCR4+ lymphocytes in chronically inflamed skin, but not in the gastrointestinal lamina propria. Moreover, TARC induces integrin-dependent adhesion of skin (but not intestinal) memory T cells to the cell-adhesion molecule ICAM-1, and causes their rapid arrest under physiological flow. Our results suggest that CCR4 and TARC are important in the recognition of skin vasculature by circulating T cells and in directing lymphocytes that are involved in systemic as opposed to intestinal immunity to their target tissues.

Chemokine CCL17↗
PubMed1999

Treatment of multicentric Castleman's disease complicated by the development of non-Hodgkin's lymphoma with high-dose chemotherapy and autologous peripheral stem-cell support.

BACKGROUND: Castleman's disease or angiofollicular lymph node hyperplasia is a rare entity with a localized/unicentric or a generalized/multicentric presentation. While surgery is curable for most localized presentations, there is limited information regarding the optimal management of the multicentric type. The latter type is associated with a poor prognoses and can be associated with the development of lymphoma and infections. PATIENTS AND METHODS: In this report we describe a case of multicentric Castleman's disease who failed steroids and chemotherapy and developed a follicular mixed lymphoma. He was treated with high-dose chemotherapy with autologous stem-cell support and remains disease at four years of follow-up. CONCLUSIONS: A long-term durable remission may be possible with high dose chemotherapy with stem-cell support. This treatment modality should be considered an option in the management of multicentric Castleman's disease.

Adult↗
PubMed1998

A novel P-selectin glycoprotein ligand-1 monoclonal antibody recognizes an epitope within the tyrosine sulfate motif of human PSGL-1 and blocks recognition of both P- and L-selectin.

Interactions between P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1) mediate the earliest "rolling" of leukocytes on the lumenal surface of endothelial cells at sites of inflammation. Previously, PSGL-1 has been shown to be the primary mediator of interactions between neutrophils and P-selectin, but studies on the ability of PSGL-1 to mediate interactions between P-selectin and other subsets of leukocytes have yielded variable and conflicting results. A novel IgG monoclonal antibody (MoAb) to human PSGL-1 was generated, and the specificity of this MoAb was confirmed by both flow cytometric analysis and Western blotting of cells transfected with human PSGL-1. This newly developed MoAb, KPL1, inhibited interactions between P-selectin expressing COS cells and either HL60 cells, neutrophils, or lymphocytes. Furthermore, KPL1 completely inhibited interactions between P-selectin and either purified CD4 T cells or neutrophils in a flow assay under physiological conditions, but had no effect on interactions of T cells or neutrophils with E-selectin. In addition, KPL1 blocked interactions between lymphoid cells transfected with L-selectin and COS cells expressing PSGL-1. The KPL1 epitope was mapped to a site within a consensus tyrosine sulfation motif of PSGL-1, previously shown to be essential for interaction with P-selectin and now shown to be essential for interaction with L-selectin, and to be distinct from the epitope identified by the PL1 function blocking anti-PSGL-1 MoAb. Two-color flow cytometry of normal leukocytes showed that while natural killer (NK) cells (CD16(+)), monocytes, CD4 and CD8 T cells, and alpha/beta and gamma/delta T cells were uniformly positive for PSGL-1, B cells expressed low levels of the KPL1 epitope. This low level of KPL1 staining was also observed immunohistologically in germinal centers, which had no detectable KPL1 staining, whereas T-cell areas (interfollicular region) were positive for KPL1. Interestingly, plasma cells in situ and interleukin-6-dependent myeloma cell lines were KPL1(+). Thus, PSGL-1 is expressed on essentially all blood neutrophils, NK cells, B cells, T cells, and monocytes. Variation in tyrosine sulfation during B-cell differentiation may affect the ability of B cells to interact with P- and L-selectin.

Animals↗
PubMed1997

A novel five-transmembrane hematopoietic stem cell antigen: isolation, characterization, and molecular cloning.

Phenotypic analysis of hematopoietic stem and progenitor cells (HSCs) has been an invaluable tool in defining the biology of stem cell populations. We have recently described the production of AC133, a monoclonal antibody (MoAb) that binds to a novel cell surface antigen present on a CD34(bright) subset of human HSCs. This antigen is a glycosylated protein with a molecular weight of 120 kD. Here, we report the molecular cloning of a cDNA encoding this antigen and show that it does not share homology with any previously described hematopoietic or other cell surface antigen(s). The AC133 polypeptide has a predicted size of 97 kD and contains five-transmembrane (5-TM) domains with an extracellular N-terminus and a cytoplasmic C-terminus. Whereas the expression of tetraspan (4-TM) and 7-TM molecules is well documented on mature and immature hematopoietic cells and leukocytes, this 5-TM type of structure containing two large (255-amino acid [aa] and 290-aa) extracellular loops is unique and does not share sequence homology with any known multi-TM family members. Expression of this protein appears limited to bone marrow in normal tissue by immunohistochemical staining; however, Northern analysis suggests that the mRNA transcript is present in a variety of tissues such as the kidney, pancreas, placenta, and fetal liver. The AC133 antigen is also expressed on subsets of CD34+ leukemias, suggesting that it may be an important early marker for HSCs, as well as the first described member of a new class of TM receptors.

ADP-ribosyl Cyclase↗
PubMed1997

Dendritic cell ontogeny: a human dendritic cell lineage of myeloid origin.

Dendritic cells (DC) have been thought to represent a family of closely related cells with similar functions and developmental pathways. The best-characterized precursors are the epidermal Langerhans cells, which migrate to lymphoid organs and become activated DC in response to inflammatory stimuli. Here, we demonstrate that a large subset of DC in the T cell-dependent areas of human lymphoid organs are nonactivated cells and belong to a separate lineage that can be identified by high levels of the interleukin 3 receptor alpha chain (IL-3Ralphahi). The CD34+IL-3Ralphahi DC progenitors are of myeloid origin and are distinct from those that give rise to Langerhans cells in vitro. The IL-3Ralphahi DC furthermore appear to migrate to lymphoid organs independently of inflammatory stimuli or foreign antigens. Thus, DC are heterogeneous with regard to function and ontogeny.

Cell Lineage↗
PubMed1996

RANTES chemokine expression in diseased and normal human tissues.

RANTES is a member of a large family of cytokines, called chemokines, which are thought to play a regulatory role in inflammatory processes. We have made recombinant human RANTES protein which was used to generate a panel of anti-RANTES monoclonal antibodies. Following characterization, select anti-RANTES monoclonal antibodies were used for immunohistologic staining of a large panel of normal, diseased and fetal tissue sections. Diseased tissues included eleven lymphomas and eight renal tumors. Most tissues were also tested in parallel for RANTES mRNA by in situ hybridization using RANTES mRNA specific oligomeric probes. As expected, most normal adult tissues contain few, if any, RANTES positive cells. In contrast, RANTES expression dramatically increases in inflammatory sites. In addition, megakaryocytes, some tumours, and select fetal tissues express high levels of RANTES message and protein. These results indicate a wider expression of RANTES than previously appreciated and suggest multiple physiologic roles for this soluble factor.

Animals↗
PubMed1995

V7, a novel leukocyte surface protein that participates in T cell activation. I. Tissue distribution and functional studies.

Among a panel of mouse mAbs generated to a human T cell clone, one mAb, V7.1, inhibited T cell activation in the mixed lymphocyte reaction and was studied further. V7.1 reacted strongly with Ag-specific T cell clones, in addition to freshly isolated monocytes and granulocytes. However, the mAb reacted weakly with freshly isolated PBLs (T cells, B cells, and NK cells), T cells stimulated with phytohemagglutinin, or Con A, and did not stain the vast majority of transformed cell lines of hemopoietic origin. Stimulation of T cells with anti-CD3, or the combination of anti-CD3 and PMA, or anti-CD3, PMA and ionomycin, markedly increased V7.1 surface staining. The mAb precipitated a single polypeptide chain of approximately 135 kDa from alloactivated T cells or monocytes, which was reduced to approximately 110 kDa after treatment with N-glycanase. The proliferative response of T cells to allogeneic monocytes or B lymphoblastoid cells was inhibited by V7.1, and inhibition was maximal when the mAb was present at the initiation of culture. V7.1 also exhibited dose-dependent inhibition of the T cell response to immobilized anti-CD3 Ab in the absence of APCs, indicating that the inhibitory effect of this Ab occurs at the T cell level. Expression of CD25 (IL-2R) on anti-CD3-activated T cells and secretion of IL-2 induced with anti-CD3 and PMA were inhibited by V7.1, whereas the Ab had no effect on T cell proliferation induced by PHA or Con A or on T cell-mediated cytotoxicity. These results indicate that V7.1 recognizes a novel leukocyte surface glycoprotein, designated V7, that is up-regulated on Ag but not lectin-activated T cells, and appears to play a role in TCR/CD3-dependent T cell activation. In an accompanying study, the gene encoding the V7 Ag is described and the molecule is shown to be a novel member of the Ig superfamily.

Adult↗
PubMed1993

Heterogeneity of CD3 antigen expression in T-cell lymphoma.

CD3 antigen expression was studied in a series of 98 T-cell lymphomas, using polyclonal antibodies which recognize this molecule in routinely processed, paraffin-embedded, tissue. We identified 40 cases in which CD3 was present on only a proportion of the neoplastic cells. This phenomenon of heterogeneous CD3 expression was commonest in pleomorphic T-cell lymphomas (22/42 cases) and in CD30 (Ki-1)-positive lymphomas (5/11 cases), and was less frequently observed in mycosis fungoides (4/18 cases) and not seen in T-cell lymphoblastic lymphoma (0/9 cases). CD3 expression was often related to cell morphology, with CD3 antigen being present on the smaller neoplastic cells but absent from the larger ones. The diagnostic significance of these observations is that, on occasion, it may be possible to diagnose a lymphoma as being of T-cell origin in paraffin sections by demonstrating a minor subpopulation of CD3-positive neoplastic cells.

CD3 Complex↗
PubMed1992

A case of Woringer-Kolopp disease with Ki-1 (CD30) + cytotoxic/suppressor cells.

BACKGROUND: Woringer-Kolopp (W-K) disease is a rare, localized, histologically malignant, but clinically indolent lymphoproliferative disorder. Most authors have regarded W-K disease as a variant of mycosis fungoides. However, a recent case suggests that W-K disease may represent a spectrum of lymphoproliferative disorders that may not be related to mycosis fungoides. OBSERVATIONS: A patient with a 40-year history of localized cutaneous eruption characterized by markedly atypical epidermotropic lymphocytes was seen at Stanford (Calif) University Hospital. The lymphocytes were predominantly CD30+ cytotoxic/suppressor T cells, an immunophenotype not previously described in W-K disease. Genotype analysis revealed a clonal rearrangement. CONCLUSIONS: The findings in our patient, along with a review of all cases previously reported in the literature, suggest that W-K disease may be an entity with a uniform clinical and histologic presentation, but one with marked immunophenotypic heterogeneity of the malignant-appearing atypical cells. Some cases showed immunophenotypic similarities to mycosis fungoides. However, in almost half of the reviewed cases, including the one presented here, the immunophenotypic differences exceeded the similarities.

Aged↗
PubMed1989

An epitope of the transferrin receptor is exposed on the cell surface of high-grade but not low-grade human lymphomas.

In attempting to identify antigens that are differentially expressed on tumor cells following transformation from follicular small cleaved cell lymphoma (FSC) to immunoblastic lymphoma (IL), we identified a unique epitope of the transferrin receptor (TfR). The epitope is available for binding in aggressive lymphomas but not in indolent lymphomas or normal cells. An immunoglobulin G2a (IgG2a) antibody that binds this epitope, Trump, was produced by screening on tumor cells from a patient who initially had a low-grade lymphoma which subsequently converted to a high-grade lymphoma. Immunoprecipitation and comodulation studies show that Trump binds to the TfR, but blocking studies and immunostaining reveal that the TfR epitope seen by Trump is distinct from the OKT9 and anti-TfR binding sites. The ability of Trump to discriminate a separate population of more highly malignant cells suggests that the expression of the Trump epitope is determined by the state of activation or degree of malignancy of the cell. In addition, it may be possible to use the Trump antibody diagnostically or therapeutically in the management of lymphomas.

Antigen-Antibody Reactions↗