Figure 2.

TCRB diversity in peripheral blood samples. (A) Rarefaction curves plotted using all data from all libraries from blood draw 1 (round symbols) and blood draw 2, taken 1 wk later (square symbols) from donor 1. Random resampling was done in triplicate, and error bars are contained within symbols. Both curves plateau, suggesting that more sequencing of either sample would not be expected to produce many new sequences. However, this tendency toward leveling is a property of rarefaction curves, and the plateau is not informative regarding absolute abundance. Hence, rarefaction curves must be interpreted with caution. (B) Accumulation analysis provides a more meaningful measure of saturation. Here we show the number of new distinct sequences found in each library (x-axis) against the total number of distinct sequences from the blood sample as a whole. The TCRB diversity within blood draw 1 from donor 1 appears to have been captured, since analyzing additional libraries would not be expected to yield many new TCRB sequences. In contrast to the rarefaction curve present in the previous panel, library-based accumulation shows that the diversity of blood draw 2 is similar to that of blood draw 1 but has not yet been fully captured. (C) Despite saturation of blood draw 1, sequences found in blood draw 2 only partially overlap, indicating that there is considerable un-sampled diversity within the peripheral blood TCRB repertoire of this individual.