ENGINEERED SECRETED T-CELL RECEPTOR ALPHA-BETA HETERODIMERS

We have produced a soluble form of a mouse alpha-beta T-cell antigen receptor (TCR) by shuffling its variable (V) and constant (C) domains to the C region of an immunoglobulin kappa-light chain. These chimeric molecules composed of V-alpha-C-alpha-C-kappa and V-beta-C-beta-C-kappa chains were efficiently secreted (up to 1-mu-g/ml) by transfected myeloma cells as noncovalent heterodimers of about 95-kDa molecular mass. In the absence of direct binding measurement, we have refined the epitopic analysis of the soluble V-alpha-C-alpha-C-kappa-V-beta-C-beta-C-kappa dimers and shown that they react with an anti-clonotypic antibody and two antibodies directed to the C domain of the TCR alpha and beta-chains. Conversely, we have raised three distinct monoclonal antibodies against the soluble TCR heterodimers and shown that they recognize surface-expressed TCRs. Two of these antibodies were found to react specifically with the products of the V-alpha-2 (V-delta-8) and V-beta-2 gene segments, respectively. When considered together, these data suggest that these soluble TCR molecules are folded in a conformation indistinguishable from that which they assume at the cell surface.