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1.

001-es BibID:BIBFORM024154
Első szerző:Szabó Gábor (biofizikus)
Cím:Cross-linking of CD4 in a TCR/CD3-juxtaposed inhibitory state : a pFRET study / Szabo G., Weaver J. L., Pine P. S., Rao P. E., Aszalos A.
Dátum:1995
Megjegyzések:Instances when T cell activation via the T cell receptor/CD3 complex is suppressed by anti-CD4 Abs are generally attributed either to the topological separation of CD4-p56(kk) from CD3, or their improper apposition. Photobleaching fluorescence resonance energy transfer measurements permitted direct analysis of these alternatives on human peripheral blood lymphocytes. Distinction between changes of relative antigen densities or positioning was made possible by simultaneously recording donor and acceptor fluorescence in the energy transfer experiment performed on homogeneous populations of flow-sorted cells. We show here that CD4 stays in the molecular vicinity of CD3, while anti-CD3 stimulation is suppressed by anti-CD4 or cross-linked HIV gp120. Our data suggest that cross-linking of CD4 through particular epitopes is capable of inhibiting activation driven by Abs binding to specific sites on CD3 without major topological sequestration of the Ags, in such a way that additional positive signals will also be affected. Thus, these and other related cases of negative signaling via CD4 may be interpreted in terms of functional uncoupling rather than a wide physical separation of CD4 from the T cell receptor-CD3 complex
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
analysis
blood
Cells
Energy Transfer
Epitopes
Fluorescence
Fluorescence Resonance Energy Transfer
Hiv
Human
lymphocyte
Lymphocytes
Photobleaching
Megjelenés:Biophysical Journal. - 68 : 3 (1995), p. 1170-1176. -
További szerzők:Weaver, James L. Pine, P. Scott Rao, P. Aszalos Adorján
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2.

001-es BibID:BIBFORM024109
Első szerző:Szabó Gábor (biofizikus)
Cím:The L-Selectin (Leu8) Molecule Is Associated with the Tcr/Cd3 Receptor - Fluorescence Energy-Transfer Measurements on Live Cells / Szabo G., Pine P. S., Weaver J. L., Rao P. E., Aszalos A.
Dátum:1994
Megjegyzések:Several accessory molecules were shown to play important roles in T cell functions and be in close proximity to the T cell receptor (TcR/CD3). The L-selectin molecule (Leu8, LAM1-1, LECAM1) also plays an important role in lymphocyte homing and proliferation. We were interested in determining the proximity of this molecule to the TcR/CD3 complex on live peripheral human T cells. Using a fluorescence energy transfer method, designed to study individual cells, we could show that L-selectin is within 170 A of the TcR/CD3 complex. Monoclonal antibody directed against the LAM1-1 (Leu8) epitope of the L-selectin molecule suppressed the mitogenic activity of antibodies specific for various CD3 epitopes in vitro. Intracellular Ca2+ mobilization obtained with wt31 followed by cross-linking antibody or with anti-CD3 was not influenced by anti-leu8 antibody. Also antibody directed against the LAM1-1 epitope did not influence the binding of the mitogenic antibodies, as shown by fluorescence-based flow cytometry. Therefore, we suggest that binding of TcR/CD3 bound mitogenic antibodies to accessory cell Fc receptors may be hindered by antibodies bound to the close proximity L-selectin molecules
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Antibodies
cell function
Cells
cytometry
Energy Transfer
Epitopes
Flow Cytometry
Fluorescence
Human
In Vitro
L-Selectin
lymphocyte
Megjelenés:Immunology and Cell Biology. - 72 : 4 (1994), p. 319-325. -
További szerzők:Pine, P. Scott Weaver, James L. Rao, P. Aszalos Adorján
Internet cím:elektronikus változat
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3.

001-es BibID:BIBFORM024106
Első szerző:Szabó Gábor (biofizikus)
Cím:CD4 changes conformation upon ligand binding / Szabo G., Pine, P. S., Weaver J. L., Rao P. E., Aszalos A.
Dátum:1992
Megjegyzések:Aurintricarboxylic acid (ATA) has been shown to block the binding site for both HIV gp120 and mAb anti-Leu 3a on CD4. We have unexpectedly found that brief treatment with greater-than-or-equal-to 1 mug/ml ATA rapidly disengages another mAb, OKT4E, after it has been bound to CD4 on human PBL. OKT4E is specific for a discontinuous epitope overlapping the MHC class II-binding region in the N-terminal CD4 domain. Interestingly, among 10 other mAb tested, only anti-Leu 8, specific for a leukocyte homing receptor is also quickly released from the cells by ATA treatment. Disengagement of the OKT4E mAb is also seen on a CD4-positive cell line (HPB-ALL) and with recombinant soluble CD4 (sCD4) bound to immobilized OKT4E. In all of these cases, disengagement is prevented if OKT4E is cross-linked, or the Leu 3a site is blocked by the mAb, but not by gp120. Photobleaching fluorescence resonance energy transfer (pFRET) measurements suggest that OKT4E is released as an indirect consequence of ATA-evoked conformational changes of CD4. Similar changes were detected as a result of gp120 binding to PBL. These data raise the possibility of a novel type of immunomodulation: induced disengagement of a bound ligand from its Ag
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
binding site
Cell Line
Cells
Energy Transfer
Fluorescence
Fluorescence Resonance Energy Transfer
Hiv
Human
ligand
Photobleaching
Megjelenés:Journal of Immunology. - 149 : 11 (1992), p. 3596-3604. -
További szerzők:Pine, P. Scott Weaver, James L. Rao, P. Aszalos Adorján
Internet cím:elektronikus változat
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4.

001-es BibID:BIBFORM024105
035-os BibID:(scopus)0026577623 (wos)A1992HH57800008
Első szerző:Szabó Gábor (biofizikus)
Cím:Epitope mapping by photobleaching fluorescence resonance energy transfer measurements using a laser scanning microscope system / Szabo G., Pine P. S., Weaver J. L., Kasari M., Aszalos A.
Dátum:1992
Megjegyzések:The donor photobleaching method (T. M. Jovin and D. J. Arndt-Jovin. 1989. Annu. Rev. Biophys. Biophys. Chem. 18:271-308.) has been adapted to an ACAS 570 (laser scanning microscope) system to measure fluorescence resonance energy transfer (FRET) on individual human peripheral blood T cells. Photobleaching was completed in approximately 100 ms in our case and it followed double-exponential kinetics. The energy transfer efficiency (E) was approximately 20% between the CD4 epitopes OKT4-FITC and Leu-3a-PE as well as between OKT4E-FITC and OKT4-PE. E was approximately 8% between OKT4-FITC and Leu-4-PE (alpha-CD3) and barely detectable (approximately 4%) from OKT4-FITC to Leu-5b-PE (alpha-CD2). The E values obtained by the photobleaching method were highly reproducible both in repeated measurement of identical samples and in experiments with different batches of cells and were in agreement with the flow cytometric donor quenching measurements. As expected, E measured between primary and secondary layers of antibodies increased (from approximately 14% to approximately 28%) when F(ab')2 fragments were substituted for whole antibody molecules as the donor. On a T cell line we mapped the distance between the idiotypic determinant of the T cell receptor (TcR) and the Leu-4 epitope of CD3 as proximal as E = 28%, as compared to E = 4% between a framework TcR epitope and Leu-4. In the latter case, however, approximately 40% less Leu-4 was bound suggesting that the antigen binding site of TcR is in close proximity with one of the two CD3 epsilon-chains, which hence are not equivalent
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Antibodies
binding site
blood
Cell Line
Cells
Energy Transfer
Epitopes
Fluorescence
Fluorescence Resonance Energy Transfer
FRET
Human
Kinetics
Photobleaching
Megjelenés:Biophysical Journal. - 61 : 3 (1992), p. 661-670. -
További szerzők:Pine, P. Scott Weaver, James L. Kasari, Mark Aszalos Adorján
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5.

001-es BibID:BIBFORM024107
Első szerző:Szabó Gábor (biofizikus)
Cím:Specific Disengagement of Cell-Bound Anti-Lam-1 (Anti-L-Selectin) Antibodies by Aurintricarboxylic Acid / Gábor Szabo Jr., James L. Weaver, P. Scott Pine, Adorján Aszalos
Dátum:1993
Megjegyzések:Brief treatment of human peripheral blood lymphocytes with the potential anti-HIV compound aurintricarboxylic acid (ATA) prompts the selective release of already bound L-selectin-specific anti-leu8 and anti-LAM1-1 antibodies from the cells. Two other anti-LAM1 antibodies, anti-LAM1-3 and anti-LAM1-5 stay antigen-bound at the same time. interestingly, the ATA-sensitive anti-leu8 strongly competes with the ATA-resistant anti-LAM1-3 for binding. Photobleaching fluorescence resonance energy transfer (pFRET) measurements on flow-sorted cells suggests that these two antibodies compete for the same epitope, while anti-LAM1-5-FITC and anti-Leu8-PE bind to distinct sites, although they also compete for binding. Combining the data on competition, pFRET and ATA effect, we suggest that the ATA sensitive anti-leu8 and resistant anti-LAM1-3 bind to overlapping but non-identical epitopes. This remarkably specific effect may be exploited for designing anti-inflammatory drugs that modulate leukocyte adhesion
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Antibodies
blood
Cells
Energy Transfer
Epitopes
Fluorescence
Fluorescence Resonance Energy Transfer
Human
lymphocyte
Lymphocytes
Photobleaching
time
Megjelenés:Molecular Immunology. - 30 : 18 (1993), p. 1689-1694. -
További szerzők:Weaver, James L. Pine, P. Scott Aszalos Adorján
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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6.

001-es BibID:BIBFORM024108
Első szerző:Weaver, James L.
Cím:The effect of ion channel blockers, immunosuppressive agents, and other drugs on the activity of the multi-drug transporter / Weaver J. L., Szabo G., Pine P. S., Gottesman M. M., Goldenberg S., Aszalos A.
Dátum:1993
Megjegyzések:The MDRI protein is an energy-dependent transport protein responsible for the multi-drug resistance seen in many tumors. A variety of drugs have been shown to inhibit the function of this pump, including compounds known to block various ion channels. The mouse lymphoma cell line L5178Y has been transduced with the human mdrI gene. Using this cell line, we have tested a number of compounds to determine whether there is a correlation between the ability to block a specific type of ion channel, or shift membrane potential, and the ability to act as an MDR-reversing agent using the fluorescent substrates Rhodamine 123 and daunorubicin as test compounds. Our results show no apparent correlation between the ability to block a specific ion channel and reversal of MDR transport ability. We have found active MDR inhibitors in compounds that affect K+, Na+, Ca++, H+, but not Cl- channels. Our data suggest that Cl-channel activity may be distinct from MDR activity. Several immunosuppressive compounds and analogs were also tested and found to be active reversing agents. Measurements suggest a significant difference in resting membrane potential between the L5178YvMDR line and the L5178Y parental cell line used in these experiments. No correlation was found between the ability of drugs to alter membrane potential and to inhibit MDR transport activity. Our results suggest that MDR transport function may be independent of the physiological movement of ions and show that a wide variety of compounds can inhibit MDR transport
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Cell Line
Daunorubicin
Human
Immunosuppressive Agents
Ion Channels
Lymphoma
mouse
Rhodamine 123
Megjelenés:International Journal of Cancer. - 54 : 3 (1993), p. 456-461. -
További szerzők:Szabó Gábor (1953-) (biofizikus) Pine, P. Scott Gottesman, Michael M. Goldenberg, Sarah Aszalos Adorján
Internet cím:elektronikus változat
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