A Direct Estimate of the Human αβ T Cell Receptor Diversity

Abstract

Generation and maintenance of an effective repertoire of T cell antigen receptors are essential to the immune system, yet the number of distinct T cell receptors (TCRs) expressed by the estimated 10 12 T cells in the human body is not known. In this study, TCR gene amplification and sequencing showed that there are about 10 6 different β chains in the blood, each pairing, on the average, with at least 25 different α chains. In the memory subset, the diversity decreased to 1 × 10 5 to 2 × 10 5 different β chains, each pairing with only a single α chain. Thus, the naı̈ve repertoire is highly diverse, whereas the memory compartment, here one-third of the T cell population, contributes less than 1 percent of the total diversity.