Generation of Antigen-Specific, LacZ-Inducible T-Cell Hybrids

The recognition of a peptide-bound major histocompatibility complex (MHC) molecule on the surface of antigen-presenting cells (APCs) is the central event in T-cell activation. The enormous complexity of the peptide pool displayed by MHC molecules makes it virtually impossible to detect physically the presence of a given peptide-MHC complex on the APC surface. Yet, T-cells have evolved to carry out precisely this function with an extraordinary efficiency, i.e., the detection of rare peptide-MHC complexes among the multitude of other peptides presented by the MHC molecules on the APC surface. Therefore, all practical assays for detecting the expression of a particular peptide-MHC complex depend on the measurement of some aspect of the T-cell response that is specifically initiated when the T-cell receptor (TCR) and its CD4 or CD8 coreceptor is engaged by the appropriate peptide-MHC complex.