Calcium signaling on Jurkat T cells induced by microbeads coated with novel peptide ligands specific to human CD3ε.

Affiliation

Ahmadi A(1), Ayyadevara VSSA(2), Baudry J(3), Roh KH(4).
Author information:
(1)Department of Chemical & Materials Engineering, University of Alabama in Huntsville, 301 Sparkman Drive NW, Huntsville, AL 35899, USA. [Email]
(2)Biotechnology Science and Engineering, University of Alabama in Huntsville, Huntsville, AL 35899, USA.
(3)Biotechnology Science and Engineering, University of Alabama in Huntsville, Huntsville, AL 35899, USA and Department of Biological Sciences, University of Alabama in Huntsville, Huntsville, AL 35899, USA.
(4)Department of Chemical & Materials Engineering, University of Alabama in Huntsville, 301 Sparkman Drive NW, Huntsville, AL 35899, USA. [Email] and Biotechnology Science and Engineering, University of Alabama in Huntsville, Huntsville, AL 35899, USA.

Abstract

CD3ε is expressed on T lymphocytes as a part of the T cell receptor (TCR)-CD3 complex. Together with other CD3 molecules, CD3ε is responsible for the activation of T cells via transducing the event of antigen recognition by the TCR into intracellular signaling cascades. The present study first aims to identify a novel peptide ligand that binds to human CD3ε in a specific manner and to perform an initial evaluation of its biological efficacy on the human T cell line, Jurkat cells. We screened a phage-display peptide library against human CD3ε using a subtractive biopanning process, from which we identified 13 phage clones displaying unique peptide sequences. One dominant phage clone displaying the 7 amino acid sequence of WSLGYTG, which occupied 90% of tested plaques (18 out of 20) after the 5th round of biopanning, demonstrated a superior binding behavior to other clones in the binding assays against recombinant CD3ε on microbeads or Jurkat cells. The synthesized peptide also showed specific binding to Jurkat cells in a dose-dependent manner but not to B cell lymphoma line, 2PK3 cells. Molecular modeling and docking simulation confirmed that the selected peptide ligand in an energetically stable conformation binds to a pocket of CD3ε that is not hidden by either CD3γ or CD3δ. Lastly, magnetic microbeads conjugated with the synthesized peptide ligands showed a weak but specific association with Jurkat cells and induced the calcium flux, a hallmark indication of proximal T cell receptor signaling, which gave rise to an enhancement of IL-2 section and cell proliferation. The novel peptide ligand and its various multivalent forms have a great potential in applications related to T cell biology and T cell immunotherapy.