HUMAN HLA-A0201-RESTRICTED CYTOTOXIC T-LYMPHOCYTE RECOGNITION OF INFLUENZA-A IS DOMINATED BY T-CELLS BEARING THE V-BETA-17 GENE SEGMENT

The major histocompatibility complex class I-restricted cytotoxic T ly mphocyte (CTL) response is important in the clearance of viral infecti ons in humans. After influenza A infection, a peptide from the matrix protein, M58-66, is presented in the context of the MHC allele HLA-A02 01 and the resulting CTL response is detectable in most HLA-A0201 subj ects. An initial study suggested that M58-66-specific CTL clones show conserved T cell receptor (TCR) alpha and beta gene segments. We have addressed the significance of this observation by determining the expr ession of V beta 17 during the development of M58-66-specific CTL line s in 21 unrelated HLA-A0201 subjects, and analyzing TCR usage by MS8-6 6-specific CTL clones. TCR V beta 17 was the dominant V beta segment u sed and CD8 V beta 17 expansion correlated with M58-66-specific lysis. Limiting dilution analysis from five subjects showed the M58-66 CTL p recursor frequency to vary between 1/54,000 and less than 1/250,000, a nd that up to 85% of the matrix peptide (M58-66)-specific CTL used the V beta 17 gene segment. The M58-66 specific CTL response was dependen t on previous viral exposure and specific V beta 17 expansion, as it w as not found in cord blood, despite a readily expandable V beta 17(+) CD8(+) T cell subpopulation. Sequence analysis of 38 M58-66-specific V beta 17 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 beta 17 gene seg ment, peripheral blood lymphocytes were depleted of CD8(+) TCR V beta 17(+) cells, before the generation of M58-66-specific CTL. In most cas es such depletion blocked or severely reduced the generation of the M5 8-66-specific response, and under limiting dilution conditions could a bolish M58-66-specific CTL precursors. These studies reveal the depend ence of this natural human immune response on a particular TCR gene se gment.