Public TCR use by herpes simplex virus-2-specific human CD8 CTLs

Abstract

Recombination of germline TCR alpha and beta genes generates polypeptide receptors for MHC peptide. Ag exposure during long-term herpes simplex infections may shape the T cell repertoire over time. We investigated the CD8 T cell response to HSV-2 in chronically infected individuals by sequencing the hypervariable regions encoding TCR alpha and beta polypeptides from T cell clones recognizing virion protein 22 aa 49-57, an immunodominant epitope. The most commonly detected TCRBV gene segment, found in four of five subjects and in 12 of 50 independently derived T cell clones, was TCRBV12-4. Nineteen to seventy-two percent of tetramer-binding cells in PBMCs were stained ex vivo with a TCRBV12 mAb. Three alpha-chain and three beta-chain public TCR sequences were shared between individuals. Public heterodimers were also detected. Promiscuous pairing of a specific TCRVA1-1 sequence with several different TCRB polypeptides was observed, implying a dominant structural role for the TCRA chain for these clonotypes. Functional avidity for cytotoxicity and IFN-gamma release was relatively invariant, except for one subject with both high avidity and unique TCR sequences and lower HSV-2 shedding. These data indicate that the CD8 response to a dominant alpha-herpesvirus epitope converges on preferred TCR sequences with relatively constant functional avidity.

Fig. 1

Selective use of TCRB gene families by HSV-2-specific CD8 T-cells. Portion of ethidium/agarose gel viewed by UV light after PCR reactions with cDNA derived from sorted tetramer B7-RPR cells from PBMC from subject 5491. Bands at the expected molecular weight were only noted for primers specific for TCRBV primers 6 and 8 (lane labels) when combined with a C-region primer.

Fig. 2

Selective expression of TCRBV12-utilizing TCRs by HSV-2-specific CD8 T-cells. PBMC from three indicated subjects were analyzed for binding of anti-CD8 mAb, tetramer B7-RPR, and a mAb specific for TCRBV12. The middle column shows TCRBV12 expression by tetramer (+) CD8 (+) cells and the right column expression by similar, tetramer (-) cells. The proportions of cells in the indicated regions of the histograms are stated.

Fig. 3

Representative dose-response curves for indicated two subjects used to establish functional avidities of HSV-2-specific CD8 clones for cytotoxicity. The concentration of peptide used to load APC is plotted versus the percent cytotoxicity at a standard effector to target ratio. Each line is a distinct T-cell clone.

Fig. 4

Summary of functional avidities for cytotoxicity for HSV-2-specific CD8 clones derived from five subjects. A summary of the pathway to obtaining T-cell clones is indicated at the bottom. Each spot represents an individual T-cell clone.

Fig. 5

Representative dose-response curves for indicated two subjects used to establish functional avidities of HSV-2-specific CD8 clones for IFN-γ release. The concentration of peptide used to load APC is plotted versus the concentration of IFN-γ in supernatants at a standard responder to stimulator ratio. Each line is a distinct T-cell clone.