Affinity and kinetics of the interactions between an alphabeta T-cell receptor and its superantigen and class II-MHC/peptide ligands.
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 alphabeta TCR and its superantigen and MHC/peptide ligands. The extracellular domains of the murine D10 TCR (Valpha2, Vbeta8.2) 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+/-0.12 x 10(4)M(-1) sec(-1) and a dissociation rate of 1.9+/-0.47 x 10(-2) sec(-1), giving a dissociation constant of 1.1 microM. 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(k) molecule containing a fused antigenic conalbumin peptide and complementary leucine zipper sequences to facilitate efficient chain pairing. The purified I A(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+/-0.19 x 10(4)M(-1)sec(-1) and a dissociation rate of 2.2+/-0.65 x 10(-2) sec(-1), giving a dissociation constant of 2.1 microM.
Khandekar
S S
SS
Procept Inc., Cambridge, MA 02139, U.S.A. khandeka@procept.com
Brauer
P P
PP
Naylor
J W
JW
Chang
H C
HC
Kern
P
P
Newcomb
J R
JR
Leclair
K P
KP
Stump
H S
HS
Bettencourt
B M
BM
Kawasaki
E
E
Banerji
J
J
Profy
A T
AT
Jones
B
B
D000818:Animals; D016367:Baculoviridae; D015374:Biosensing Techniques; D002478:Cells, Cultured; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D008213:Lymphocyte Activation; D009036:Moths; D010455:Peptides / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D012995:Solubility; D013057:Spectrum Analysis; D018089:Superantigens / Q000378:metabolism*
D000949:Histocompatibility Antigens Class II; D008024:Ligands; D010455:Peptides; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011993:Recombinant Fusion Proteins; D018089:Superantigens