Impact of chimeric immune receptor extracellular protein domains on T cellfunction

Chimeric immune receptors (CIR) encompass tumor- or virus-specific ligands or antibodies fused to the signaling domains of either the T cell receptor or Fc receptor T cells expressing these receptors recapitulate the cytopath ic effects mediated by the T cell receptor and allow the targeting of tumor or virus infected cells in an MHC-independent manner. With this technology large numbers of T cells with redirected target specificity can be generat ed. To define the structural features of recombinant CIRs required for opti mal function, a panel of five closely related CIRs with identical target sp ecificity were generated. These receptors recognized HIVenv through the sin gle chain Fv (scFv) of an anti-gp120 antibody. These scFv-zeta receptors we re constructed to include alternative extracellular spacer and transmembran e protein domains derived from members of the immunoglobulin supergene fami ly. The effect of these alternative extracellular protein domains on recept or stability, antigen affinity and T cell activity was assessed. We demonst rate that modifying the extracellular protein domains of the anti-HlV(env) CIRs significantly impacted receptor stability and substrate binding affini ty and that these effects, and not simply the level of cell surface express ion, correlated most strongly with changes in CIR-mediated killing. These s tudies will aid in the rationale design of recombinant CIRs for the immunot herapy of viral infections, cancer and other diseases.