Human HLA - A 0201 - restricted Cytotoxic T Lymphocyte Recognition of Influenza A Is Dominated by T Cells Bearing the V / 317 Gene Segment

The major histocompatibility complex class I-restricted cytotoxic T lymphocyte (CTL) response is important in the clearance of viral infections in humans. After influenza A infection, a peptide from the matrix protein, M58-66, is presented in the context of the MHC allele HLA-A0201 and the resulting CTL response is detectable in most HLA-A0201 subjects. An initial study suggested that M58-66-specific CTL clones show conserved T cell receptor (TCR) c~ and gene segments. We have addressed the significance of this observation by determining the expression of V317 during the development of M58-66-specific CTL lines in 21 unrelated HLA-A0201 subjects, and analyzing TCR usage by M58-66-specific CTL clones. TCR V317 was the dominant V3 segment used and CD8 V~17 expansion correlated with M58-66-specific lysis. Limiting dilution analysis from five subjects showed the M58-66 CTL precursor frequency to vary between 1/54,000 and less than 1/250,000, and that up to 85% of the matrix peptide (M58-66)-specific CTL used the V317 gene segment. The M58-66 specific CTL response was dependent on previous viral exposure and specific V317 expansion, as it was not found in cord blood, despite a readily expandable V317 + CD8 + T cell subpopulation. Sequence analysis of 38 M58-66-specific V317 transcripts from 13 subjects revealed extensive conservation in the CDR3 region including conservation of an arginine-serine motif. To test the dependence of this CTL response on the V[317 gene segment, peripheral blood lymphocytes were depleted of CD8 + TCR V317 + cells, before the generation of M58-66-specific CTL. In most cases such depletion blocked or severely reduced the generation of the M58-66-specific response, and under limiting dilution conditions could abolish M58-66-specific CTL precursors. These studies reveal the dependence of this natural human immune response on a particular TCR gene segment.