ANTIBODIES TO SOLUBLE HUMAN T-CELL RECEPTOR-BETA CHAIN RECOGNIZE MULTIPLE EPITOPES ON CELL-SURFACE TCR

The T cell receptor (TcR) is an integral membrane protein occurring as a disulfide linked heterodimer, non-covalently associated with CD3 on the surface of T lymphocytes. Antibodies to the TcR have been shown to be effective for treating autoimmune disorders in animals. We describe here a method for producing antibodies to cell surface determinants of the human TcR, using a soluble form of the receptor as antigen. Soluble Valpha1.2, Vbeta8.1, Vbeta11 TcR chains are expressed from a construct in which the extracellular domains of the TcR are fused to the mouse gamma2a heavy chain constant region lacking the C(H)1 domain. These chimeric molecules contain both immunoglobulin and TcR determinants, as revealed by antibody probes. Amino-terminal sequence analysis of a chimeric Vbeta8.1 molecule indicates that the TcR leader peptide is correctly processed from the soluble form. Antibodies raised against the soluble human Vbeta8.1 molecule recognize the native determinants on Jurkat cells, and on natural T cells derived from resting human peripheral blood lymphocytes. Epitope mapping studies using competitive binding assays suggest that the anti-Vbeta8 antibodies produced using soluble antigen recognize multiple overlapping determinants on the cell surface form of the TcR.