B-cell evolution and antibody optimization
Germinal centers are microstructures in lymph nodes where B-cells undergo somatic hypermutation and Darwinian selection. B-cells with higher binding affinity to the antigen are preferentially rescued by T-helper cells. This iterative mutation-selection cycle (Darwinian evolution at cellular scale) produces antibodies with dramatically improved affinity — a process taking ~2 weeks. Here each B-cell is a point in a 2D antibody shape space; the antigen is the target.