Statistical analysis of sharing in antibody repertoires

Adaptive immunity's success relies on the extraordinary diversity of protein receptors on B cell membranes. Recent progress in deep sequencing methods has been followed by the development of probabilistic models characterizing repertoire sequence distributions. Here we present a statistical approach defined in terms of a probabilistic V(D)J recombination model enhanced by a selection factor that describes repertoire diversity and that predicts with high accuracy its level of publicness, i.e. the number of sequences that will be shared between any number of individuals. While the model shows perfect agreement with healthy repertoires it clearly underestimates sharing between repertoires affected by a common antigen. This deviation is a sign of a stronger antigen driven selection that opens the possibility of finding antigen-specific antibodies.