Symmetric and Asymmetric Division Models

By Steven Reiner

How does the body produce the diversity in T-cell fates that are essential for immunity? The symmetric division model predicts that the fate of each naïve T-cell is determined by the cytokines the dendritic cell produces: one cell, one fate. The asymmetric division model predicts that two fates arise from a single na￯ve T-cell. The effector cells defend against the microbe, while the memory cells replenish the loss of the rare na￯ve T-cells, which specifically match the pathogen.