Biomedical subjects

E Geissinger

Publications and source records attributed to E Geissinger.

5 recordsLinked to original sources

PubMed2007

[Peripheral NK/T-cell lymphoma].

Peripheral T-cell lymphomas comprise 8% of the malignant lymphomas in Germany. About 25% of these cases present primarily in extranodal localizations. Such localizations are typical for the respective disease and form the basis for the classification of extranodal peripheral T-cell lymphoma. The morphology, immunophenotype and lineage specificity of the tumor cells (originating from T- or NK-cells) is only secondary for the classification. Extranodal NK/T-cell lymphomas of the nasal type are characterized by an angiocentric growth pattern and large confluent areas of necrosis. In addition, there is a clonal infection by Epstein-Barr virus in the T-lymphocytes. In the differential diagnosis, B-cell lymphomas are more frequent at all localizations than T- or NK-cell lymphomas.

Diagnosis, Differential↗

PubMed2007

[Cutaneous B-cell lymphoma. Classification and diagnostics].

Primary cutaneous B-cell lymphomas include cutaneous follicle centre lymphoma (PCFCL), cutaneous marginal zone B-cell lymphoma (PCMZL) and cutaneous diffuse large B-cell lymphoma (PCLBCL) "leg type" which are the three main types in the new WHO-EORTC classification for cutaneous lymphomas. PCFCL and PCMZL are indolent lymphomas with an excellent prognosis while PCLBCL shows an aggressive clinical course. All three types must be distinguished from a secondary skin involvement by systemic lymphomas. Since histological and immunohistochemical findings are not decisive, making this distinction requires appropriate staging procedures. In contrast, the pathologist can make an important contribution to the differential diagnosis between neoplastic and reactive cutaneous lymphoproliferations.

Humans↗

PubMed2006

Nodal peripheral T-cell lymphomas correspond to distinct mature T-cell populations.

Peripheral T-cell lymphomas (PTCL) have not been successfully correlated with specific developmental stages of reactive T-cells. Mature T-cells pass through distinct stages upon antigen encounter. Naïve T-cells are CD45RA(+)/CD45R0(-)/CD27(+)/CCR7(+). After antigen contact they replace CD45RA expression with CD45R0. The mature T-cells differentiate to central memory cells, which retain CD27 and CCR7, or to effector memory cells, which lose expression of both molecules depending on the strength of the antigen interaction. In this study, we evaluated lymph node biopsies from eight PTCL-not otherwise specified (PTCL-NOS), seven angioimmunoblastic T-cell lymphomas (AILT), and 15 anaplastic large cell lymphomas (ALCL). Detection of tumour cells with antibodies that recognize specific rearranged T-cell receptor Vbeta segments allowed us to investigate the expression of various differentiation-associated molecules. Results were analysed by hierarchical cluster analysis. All AILT and ALCL showed a homogeneous effector cell phenotype (CD45RA(-)/CD45R0(+)/CD27(-)), but differed in the cytotoxic and activation markers expressed. Several (5/8) PTCL-NOS clustered together; these cases all exhibited a CD4(+) central memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(+)) and four expressed the lymph node homing receptor CCR7. In conclusion, AILT and ALCL tumour cells correspond to different subsets of effector cells, while a subset of PTCL-NOS correlates with a non-effector T-cell population.

CD4-Positive T-Lymphocytes↗

PubMed2005

Extrafollicular proliferation of B cells in the absence of follicular hyperplasia: a distinct reaction pattern in lymph nodes correlated with primary or recall type responses.

AIMS: Extrafollicular activation of B cells is rarely observed in human lymph nodes. The aim of this study was to extensively analyse the expression of surface molecules and transcription factors in four such cases, comparing them with follicular B cells and medullary cord plasma cells. METHODS AND RESULTS: Various combinations of B-cell-related surface markers and transcription factors were studied by triple immunofluorescence. While in the germinal centre, reactive immunoglobulin production occurred exclusively in non-proliferating cells, in extrafollicular activation proliferation of B cells and immunoglobulin production coexisted. In two of these cases proliferating cells were mainly IgG+CD27+, i.e. derived from class-switched postgerminal centre memory B cells. Some of these cells expressed CD30. In the other two cases, immunoglobulin-forming cells were non-class-switched IgM+CD27- B cells, representing a primary expansion of naive B cells. CONCLUSIONS: Extrafollicular B-cell activation is the morphological correlate of rapid B-cell responses that do not involve the germinal centres. It is pathogenetically heterogeneous, comprising primary responses that occur prior to, or independent of, germinal centre reaction or memory cell activation in recall responses.

Antigens, CD↗

PubMed1998

Signalling by the oncogenic receptor tyrosine kinase Xmrk leads to activation of STAT5 in Xiphophorus melanoma.

Overexpression of the mutationally activated Xmrk receptor initiates the formation of hereditary malignant melanoma in the fish Xiphophorus. In addition to transcriptional overexpression a cell-type specific signal transduction is essential for Xmrk mediated tumor formation. To elucidate the consequence of Xmrk signalling and to identify target proteins that characterize the tumor phenotype, we analysed proteins that are strongly tyrosine phosphorylated in the fish melanoma cell line PSM. One of the most prominent phosphotyrosine proteins was found to be the signal transducer and activator of transcription STAT5. In a heterologous cell system (murine pro B-cells), activation of the Xmrk kinase in a chimeric receptor induced tyrosine phosphorylation, nuclear translocation and DNA binding of STAT5. Following receptor stimulation, expression of the STAT5 specific target genes cis, osm and pim-1 was induced. In Xiphophorus PSM cells STAT5 was found to be preferentially localized in the nucleus, but treatment with tyrphostin AG555, a specific Xmrk kinase-inhibitor, blocked nuclear localization. In these cells as well as in Xiphophorus melanoma expression of pim-1 and constitutive DNA-binding activity of STAT5 was detectable. This constitutive activity was higher in malignant than in benign melanomas, indicating that STAT5 activation is correlated with the malignancy of these tumors.

Animals↗