Germinal Center Affinity Maturation

In germinal centers (GCs), B cells undergo rapid somatic hypermutation (SHM) — mutations in antibody genes — followed by selection: cells with higher affinity for antigen receive survival signals (from T follicular helper cells), while low-affinity cells die. Repeated rounds of mutation+selection drive exponential improvement in affinity (affinity maturation). The mutation-selection balance: too little mutation → stagnation; too much → error catastrophe.