(A) The distribution of cells expressing CD57 and CD28 within the CD8⁺ T cell population from a healthy CMV seropositive adult. (B) From the TCR β chain of a Vβ17⁺ pp65 peptide 69-specific CTL clone of this donor, we designed an oligonucleotide probe based on the nucleotide sequence of the hypervariable region and the ends of the adjoining V and J regions.

mRNA was extracted from sorted PBMC, and cDNA was synthesised and amplified using a Vβ17-specific primer and a Cβ-specific primer. A positive control sample of cDNA of the original CTL clone and a negative control sample from pooled PBMC of four healthy donors was also amplified at the same time by using the same primers. PCR products were blotted onto a filter, which was first probed with the labelled clonotypic probe. By stripping the filter and reprobing with a conserved constant region-specific probe that detects all TCRs, it was possible to calculate the relative abundance of clonotype sequence compared to the total sequence within Vβ17.