CD4+ and CD8+ circulating alpha/beta T-cell repertoires are equally complex and are characterized by different levels of steady-state TCR expression

The repertoire complexity of CD4+ and CD8+ T cells was measured in three healthy blood donors for a number of TCR BV gene families by TCR spectratyping. This method subdivides V family-specific PCR products based on CDR3 length. Genomic DNA was analyzed to determine the distribution of the cells bearing particular V-J rearrangements. cDNA was analyzed to measure the levels of transcripts arising from those same cells. The complexity and distribution of T cells in each lineage were equal for most BV families. Certain families showed frequent skewing in CD8 cells. Analysis of the intensity profiles of RNA versus DNA spectratypes indicated that in general, there is a constant ratio of transcript per cell for all rearranged sizes within a particular family. This ratio appeared higher in CD4 cells. Thus, steady-state levels of TCR mRNA were measured and found to be higher in CD4+ than in CD8+ cells.