RT Journal Article
SR Electronic
T1 Fluctuating fitness shapes the clone size distribution of immune repertoires
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 021923
DO 10.1101/021923
A1 Jonathan Desponds
A1 Thierry Mora
A1 Aleksandra M. Walczak
YR 2015
UL http://biorxiv.org/content/early/2015/07/05/021923.abstract
AB The adaptive immune system relies on the diversity of receptors expressed on the surface of B and T-cells to protect the organism from a vast amount of pathogenic threats. The proliferation and degradation dynamics of different cell types (B cells, T cells, naive, memory) is governed by a variety of antigenic and environmental signals, yet the observed clone sizes follow a universal power law distribution. Guided by this reproducibility we propose effective models of somatic evolution where cell fate depends on an effective fitness. This fitness is determined by growth factors acting either on clones of cells with the same receptor responding to specific antigens, or directly on single cells with no regards for clones. We identify fluctuations in the fitness acting specifically on clones as the essential ingredient leading to the observed distributions. Combining our models with experiments we characterize the scale of fluctuations in antigenic environments and we provide tools to identify the relevant growth signals in different tissues and organisms. Our results generalize to any evolving population in a fluctuating environment.