Affinity and kinetics of the interactions between an alpha beta T-cell receptor and its superantigen and class II-MHC/peptide ligands

• Published in: Molecular immunology Vol. 34; no. 6; pp. 493 - 503
• Main Authors: Khandekar, S S, Brauer, P P, Naylor, J W, Chang, Hsiu-Ching, Kern, P, Newcomb, J R, Leclair, K P, Stump, H S, Bettencourt, B M, Kawasaki, E, Banerji, J, Profy, A T, Jones, B
• Format: Journal Article
• Language: English
• Published: 01.04.1997
• ISSN: 0161-5890
• DOI: 10.1016/S0161-5890(97)00044-8

Immune activation is mediated by a specific interaction between the T-cell receptor (TCR) and an antigenic peptide bound to the major histocompatibility complex (MHC). T-cell activation can also be stimulated by superantigens which bind to germline-encoded variable domain sequences of certain TCR beta -chains. We have used a surface plasmon resonance biosensor to characterize the molecular interactions between a class II-restricted alpha beta TCR and its superantigen and MHC/peptide ligands. The extracellular domains of the murine D10 TCR (V alpha 2, V beta 8.2) were expressed in insect cells and secreted as a disulfide-linked heterodimer. In the absence of MHC class II, purified soluble D10 TCR bound to Staphylococcus aureus enterotoxin C2 with an association rate of 1.69 plus or minus 0.12 x 10 super(4) M super(-1) sec super(-1) and dissociation rate of 1.9 plus or minus 0.47 x 10 super(-2) sec super(-1), giving a dissociation constant of 1.1 mu M. Binding of the TCR to S. aureus enterotoxin B was barely detectable and could not be measured accurately due to the rapid dissociation rate. Soluble D10 TCR also bound to a soluble murine MHC class II I-A super(k) molecule containing a fused antigenic conalbumin peptide and complementary leucine zipper sequences to facilitate efficient chain pairing. The purified I-A super(k) chimera specifically stimulated proliferation of the D10 T-cell clone, and bound to immobilized soluble D10 TCR with an association rate of 1.07 plus or minus 0.19 x 10 super(4) M super(-1) sec super(-1) and a dissociation rate of 2.2 plus or minus 0.65 x 10 super(-2) sec super(-1), giving a dissociation constant of 2.1 mu M.