Late CMV-specific CD4⁺ T cells have a very restricted TCR Vβ usage. (A) Pictures show the bands on gel retrieved after PCRs for the different Vβ families of patient 1. Analysis was performed on cDNA obtained after amplification of total RNA isolated from the different sorted CMV-specific CD4⁺ T-cell populations. Arrows on the right side indicate the height at which the specific bands for the Vβ families can be found. Smaller bands at the bottom of the picture are primer dimers and should therefore not be considered specific. Numbers on the right indicate the number of Vβs present in that sample. (B) Results of the spectratype of Vβ families which were found in both early and late CMV-specific CD4⁺ T-cell populations of patient 1. Each peak represents a CDR3 region with a certain length spaced by 3 nucleotides. Numbers indicate the corresponding Vβ; on the left side, the different cell populations are mentioned. N.D. indicates not detectable in that cell population. (C) Figure shows bands obtained after specific PCR based on sequence found in Vβ8 of CD4⁺CD28^– T cells of patient 1.