Is the selection for a long lived repertoire the same as that for a repertoire responding to acute disease? Thoughts on immune repertoire selection across multiple time scales.

In my presentation I will suggest different modes of selection that could underlie how immune repertoires change during acute immune responses and over our lifetime. When considering the immune system over a lifetime we must recognize that this co-operative behavior involves selection at multiple time scales and instances. As we age our immune repertoires are comprised more and more of clones (sets of cells with a common ancestor and receptivity) that have expanded due to previous responses. In the B cell repertoire as expansion happens together with mutation this will also lead to novel receptor affinities. They type of selection process that leads short term clonal expansion and survival need not be the one that allows long term survival of the clone and may effect which members of a clone expand in an immune response and which survive long term. How we combine these forces of selection can radically change the type of affinities and level of poly-reactivity we expect to see in the immune repertoire.