A FUNCTIONALLY SIGNIFICANT ALLELIC POLYMORPHISM IN A T-CELL RECEPTOR V-BETA GENE SEGMENT

The effect of an allelic polymorphism in the BV1S1 gene segment on rec ognition of major histocompatibility complex (MHC)-peptide complexes b y a specific T cell receptor (TCR) was studied using RBL 2H3 cells tra nsfected with TCR-CD3 zeta chimeric receptors. An HLA-A2-restricted hu man immunodeficiency virus (HIV) pol-specific cytotoxic T lymphocyte ( CTL) clone utilizing the BV1S1A2 gene in combination with AV2S1A2 was identified and the extracellular domains of the TCR were fused to CD3 zeta. In degranulation assays RBL 2H3 transfectants expressing this re ceptor maintained the specificity of the parental CTL clone. The allel ic variant BV1S1A1N1 containing a glutamine for histidine substitution at position 48 in the loop of the second complementarity-determining region was generated by site-directed mutagenesis. Transfection of thi s molecule as a CD3 zeta chimera together with the original AV2S1A2 CD 3 zeta molecule resulted in cell surface expression of both chains but a loss of recognition of HLA-A2 HIV pol peptide-pulsed targets. The e ffect of this polymorphism on MHC-peptide recognition supports current models of TCR MHC-peptide interaction and provides evidence for a fun ctional role for polymorphism in the TCRV genes.