The L-selectin (Leu8) molecule is associated with the TcR/CD3 receptor; fluorescence energy transfer measurements on live cells.
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.
Szabo
G
G
Department of Biophysics, University Medical School of Debrecen, Hungary.
Pine
P S
PS
Weaver
J L
JL
Rao
P E
PE
Aszalos
A
A
D017252:CD3 Complex / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000032:analysis* / Q000276:immunology; D002455:Cell Division; D004261:DNA Replication; D004735:Energy Transfer; D000939:Epitopes / Q000276:immunology; D006801:Humans; D019041:L-Selectin; D007834:Lasers; D008213:Lymphocyte Activation; D016853:Muromonab-CD3 / Q000276:immunology; D010777:Photochemistry; D011485:Protein Binding; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000032:analysis*; D011961:Receptors, Fc / Q000378:metabolism; D015398:Signal Transduction; D013050:Spectrometry, Fluorescence; D013601:T-Lymphocytes / Q000276:immunology / Q000648:ultrastructure*
D017252:CD3 Complex; D015815:Cell Adhesion Molecules; D000939:Epitopes; D016853:Muromonab-CD3; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011961:Receptors, Fc; D019041:L-Selectin; D002118:Calcium