In order to identify and potentially react against unknown proteins, B and T lymphocytes both display a unique type of receptor which has the particularity of including a highly variable region. These receptors are generated randomly at the cells' infancy, and, in the case of B-cells, can undergo additional mutations in order to increase their reactivity and specificity.

The set of all these receptors is called the immune repertoire. This is what I’m interested in, usually. These immune repertoires are large and diverse, and immunity, even against one specific pathogen, never involves only one receptor. So statistical methods and systemic views tend to have some power to understand this system.

The B-cell repertoire is particularly interesting. During an infection, B-cells start accumulating in the lymph nodes and mutate in order to display receptors that can bind the outsider’s proteins.

This process, called affinity maturation, is similar to Darwinian evolution. B-cells multiply and the ones that can bind most efficiently the antigen survive. This leads to the creation of clonal families, closely related B-cells that have evolved to bind a specific antigen.

To study this process we are combining computational study of human B-cell repertoire and in-vitro affinity measurements using yeast display technology.