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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
Internet cím:	elektronikus változat Intézményi repozitóriumban (DEA) tárolt változat DOI
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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 Intézményi repozitóriumban (DEA) tárolt változat DOI
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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 Intézményi repozitóriumban (DEA) tárolt változat
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