TCR signaling can enhance the avidity of CD28 ligand binding. Mariano Sanchez-Lockhart Ana V. Rojas Margaret M. Fettis Richard Bauserman Trissha R. Higa Hongyu Miao Richard E. Waugh Jim Miller 10.1371/journal.pone.0089263.g001 https://plos.figshare.com/articles/figure/_TCR_signaling_can_enhance_the_avidity_of_CD28_ligand_binding_/943312 <p>(<b>A</b>) Images from a cell adhesion assay. Top, a resting T cell and CD80-coated bead brought into contact using micropipets. Middle, the same T cell 30s later after the cell and bead were separated. No adhesion was observed. Bottom, image of a T cell bound to an anti-CD3 coated bead, which is out of the plane of focus, but clearly distal to the site of interaction of the T cell with the CD80-bead. This image was taken shortly after the T cell was pulled away from the CD80-bead. In this case, the T cell-CD80-bead adhesion has caused the T cell to dislodge from the micropipet. (<b>B</b>) Cell frequency adhesion of in vitro primed and resting WT DO11.10 T cells to control beads (None) or beads coated with CD80 (CD80-Fc) in the absence (Unstim, empty bars) and after (Anti-CD3; filled bars) stimulation. No increase in adhesion to CD80 was detected when cells were stimulated with beads coated with anti-MHC class I (not shown). (<b>C</b> and <b>D</b>) WT and CD28-deficient T cells were primed with CD80/CD86-negative APC to reduce upregulation of CTLA-4. (<b>C</b>) Flow cytometry of CTLA-4 expression on WT (thin line) and CD28-deficient (thick line) T cells after in vitro priming. Isotype control (filled) and WT T cells primed in the presence of CD28 costimulation (dashed line) are included as negative and positive controls. (<b>D</b>) Cell frequency adhesion of WT and CD28-deficient (CD28KO) T cells that were primed with CD80/CD86-negative cells, to CD80-beads in the absence (Unstim) and after (Anti-CD3) stimulation. (<b>E</b>) Adhesion frequency of WT and CTLA-4-deficient (CTLA-4KO) T cells to control beads (None) or beads coated with increasing concentrations of CD80 in the absence (Unstim) and after (Anti-CD3) stimulation. Cell adhesion data are presented as mean ± SD of the adhesion frequency for individual cells (25 impingements each; n = 9–10, except for 62.5 ng/ml CD80-Fc in panel E, n = 6; p values for t tests between samples are shown; ns, not significant).</p> 2014-02-24 03:32:16 Biochemistry proteins Immune system proteins Protein interactions protein structure T-cell receptors Transmembrane proteins Biomacromolecule-ligand interactions Macromolecular assemblies biophysics immunology Immune cells t cells Immune response immunomodulation Molecular cell biology Signal transduction Mechanisms of signal transduction crosstalk Membrane receptor signaling Immunologic receptor signaling Signaling in cellular processes Transmembrane signaling cell adhesion Computer modeling Computerized simulations avidity cd28 ligand