Biomedical subjects

S Isenmann

Publications and source records attributed to S Isenmann.

59 records · Page 4Linked to original sources

PubMed1993

Identification of a glycoprotein ligand for E-selectin on mouse myeloid cells.

E-selectin is an inducible endothelial cell adhesion molecule for neutrophils which functions as a Ca(2+)-dependent lectin. Using a recombinant, antibody-like form of mouse E-selectin, we have searched for glycoprotein ligands on mouse neutrophils and the neutrophil progenitor cell line 32D cl 3. We have identified a 150-kD glycoprotein as the only protein which could be affinity-isolated with soluble E-selectin from [35S]methionine/[35S]cysteine-labeled 32D cl 3 cells. Binding of this protein was strictly Ca(2+)-dependent, was blocked by a cell adhesion-blocking mAb against mouse E-selectin, and required the presence of sialic acid on the 150-kD ligand. This glycoprotein was also affinity-isolated from mature neutrophils, in addition to a minor component at 250 kD, but could not be isolated from several other non-myeloid cell lines. The 150-kD glycoprotein was the only protein from 32D cl 3 cells, which was detectable by silver-staining after a one-step affinity-isolation.

Animals↗

PubMed1993

Five tumor necrosis factor-inducible cell adhesion mechanisms on the surface of mouse endothelioma cells mediate the binding of leukocytes.

We have distinguished five TNF-alpha-inducible cell adhesion mechanisms on microvasculature-derived endothelioma cells of the mouse which mediate the binding of different types of leukocytes. Three of these mechanisms could be identified as the mouse homologs of ICAM-1, VCAM-1, and E-selectin, of which the latter was defined by the novel mAb 21KC10. The fourth TNF-alpha-inducible cell adhesion mechanism was blocked by antibodies specific for mouse P-selectin. We have recently shown that TNF-alpha stimulates the synthesis of P-selectin in mouse endothelioma cells (A. Weller, S. Isenmann, D. Vestweber. 1992. J. Biol. Chem. 267:15176-15183). Here we show that this stimulation leads to maximal cell surface expression levels within 4 h after stimulation while the same endothelioma cells are also able to upregulate P-selectin at the cell surface within minutes after stimulation with PMA. Both effects are additive. The fifth TNF-induced cell adhesion mechanism is defined by mediating the binding to the mouse monocyte/macrophage cell line J774. This adhesion mechanism is not inhibited by antibodies against any of the other four CAMs; it functions well at 7 degrees C (in contrast to ICAM-1 and VCAM-1) and it is as active after 16 h of TNF induction as after 4 h (in contrast to E- and P-selectin). Furthermore, this new adhesion mechanism only functions on two of three endothelioma cell lines and is undetectable on the third, although ICAM-1, VCAM-1, E-selectin, and P-selectin could be demonstrated to function well on this cell line. Thus, in addition to the three known TNF-inducible CAMs, ICAM-1, VCAM-1, and E-selectin, also P-selectin and a fifth, as yet molecularly undefined cell adhesion mechanism, are TNF inducible at the cell surface of mouse endothelioma cells.

Animals↗

PubMed1993

VCAM-1 is not involved in LPAM-1 (alpha 4 beta p/alpha 4 beta 7) mediated binding of lymphoma cells to high endothelial venules of mucosa-associated lymph nodes.

The migration of lymphocytes from the blood into various lymphoid organs (lymphocyte homing) occurs in specialized high endothelial venules (HEV). Homing of lymphocytes into mucosa-associated lymph nodes in the mouse is mediated at least in part by the lymphocyte homing receptor LPAM-1, an integrin which has been identified as the heterodimer alpha 4 beta p (alpha 4 beta 7 in humans). The HEV-ligand for this integrin in the homing process has not yet been identified. VCAM-1, a cytokine-inducible, endothelial adhesion molecule for lymphocytes and monocytes, was recently demonstrated in vitro to be a ligand for the alpha 4 beta p integrin. We have tested whether VCAM-1 could be a candidate for an alpha 4 beta p ligand on HEV. Two findings strongly argue against this possibility: First, an anti-VCAM-1 monoclonal antibody (mAb) failed to block the binding of the mouse T-lymphoma TK-1 to HEV in cryostat sections of mesenteric lymph nodes, even though this antibody blocked alpha 4 beta p mediated binding of TK-1 cells to VCAM-1 on TNF-alpha-activated mouse endothelioma cells. Second, expression of VCAM-1 on lymph node endothelium was undetectably low as tested by immunofluorescence staining of mouse tissue sections using four different mAbs against mouse VCAM-1, three of which are described in this report. Surprisingly, expression of VCAM-1 on lymph node endothelium was not found even in mice which had been treated systemically with high doses of TNF-alpha or LPS, although VCAM-1 expression was strongly induced on endothelial of all other organs that were analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Cloning of the mouse endothelial selectins. Expression of both E- and P-selectin is inducible by tumor necrosis factor alpha.

E-selectin (ELAM-1) and P-selectin (GMP-140, PADGEM, CD62) have both been described as human endothelial cell adhesion molecules for neutrophils and monocytes. Cell surface appearance of these two proteins on human umbilical vein endothelial cells can be regulated by different mechanisms: E-selectin is transcriptionally induced, within hours, by tumor necrosis factor alpha (TNF-alpha) while P-selectin is transported from storage granules to the plasma membrane within minutes upon induction by various stimulating agents. We have obtained cDNA clones covering the full-length coding sequence of the homologous mouse proteins for both endothelial selectins. We show that synthesis of mouse P-selectin, like that of E-selectin, is transiently induced by TNF-alpha in several endothelioma cell lines derived from different mouse tissues. This induction was monitored on both the RNA as well as the protein level. The TNF induced, newly synthesized P-selectin protein was detected on the cell surface. Protein expression of P-selectin increased with a slightly lower rate than expression of E-selectin. In organ cultures of lung tissue from TNF-injected mice, the synthesis of P-selectin was clearly elevated compared to control mice. The bovine P-selectin homolog recognized by cross-reaction with anti-mouse P-selectin antibodies was also TNF-inducible in primary capillary endothelial cells from adrenal cortex and in aorta-derived endothelial cells. Thus, P-selectin can be regulated on two different levels. While the transport of stored P-selectin to the cell surface is controlled by regulated secretion of storage granules, the synthesis and surface expression can be induced by TNF-alpha similarly to that of E-selectin.

Amino Acid Sequence↗

PubMedDate not supplied

Tuberculoma mimicking meningioma of the falx cerebri. PCR diagnosis of mycobacterial DNA from formalin-fixed tissue.

We describe a 47-year-old patient with intracerebral tuberculoma of the falx cerebri and fronto-parietal cerebral cortex. The patient presented after a single episode of epileptic seizures. Computed tomography and MRI scans were suggestive of meningioma. At surgery a granulomatous tumor was removed that adhered to the cerebral cortex. The diagnosis of tuberculoma was verified by histology and growth in culture of mycobacterium tuberculosis. The patient recovered after surgery and chemotherapy. Three years later we confirmed the diagnosis using polymerase chain reaction for mycobacterial DNA sequences on the formalin-fixed, paraffin-embedded tissue.

Brain↗