A 3-DOMAIN T-CELL RECEPTOR IS BIOLOGICALLY-ACTIVE AND SPECIFICALLY STAINS CELL-SURFACE MHC PEPTIDE COMPLEXES/

We have expressed in bacteria a single-chain T cell receptor (scTCR) w ith specificity for an HIV gp120-derived peptide bound to the murine M HC-I molecule, H-2D(d). This scTCR consists of V alpha covalently link ed to the V beta C beta domains that was solubilized, refolded, and pu rified in high yield. Specific binding of the scTCR to MHC/peptide com plexes was demonstrated by surface plasmon resonance, with a K-d of 2 to 8 x 10(-6) M. This scTCR specifically inhibited T cell activation, and stained cell surface MHC/peptide complexes as measured by cytofluo rimetry. The preservation of binding specificity by such a three-domai n scTCR suggests that this structure is sufficient for specific MHC/pe ptide recognition and that this strategy will be of general use as app lied to other TCR.