Diversity of Human αβ T Cell Receptors

(a = alpha) et al. (1) estimated an average diversity 9 * 10^5 different b chains and 4.5 * 10^5 different a chains in the human nai¨ve T repertoire. To calculate the total T cell diversity, the b-chain diversity was within a certain variable (V) gene , Va12^+, comprising 2.5% of the total -chain repertoire. Finding in this particular an estimated total of 6 * 105 different ß chains (i.e., two-thirds of the total ß-chain ), Arstila et al. suggested that the T cell receptor (TCR) diversity comprises least (6 * 105) * 40 = 2.4 * 10^7 aß combinations (1). The authors that this is only a lower bound, the calculation assumes that the ß that do bind at least one Va12 chain only one of the 4.5 * 10^5 different a in the Va12^+ family. If each ß chain within the Va12^+ family were to bind average of n different Va12 chains instead, total estimated TCR diversity would be -fold higher than this lower bound.