Germinal centers are typically divided into dark and light zones. Clark and colleagues identify ‘gray zone’ cyclin B1+ B cell clusters as sites of ongoing cell proliferation, and these cells are distinct from dark zone B cells that undergo AID-dependent somatic hypermutation. This separation of function safeguards B cells undergoing DNA replication against potential mutagenic events that could result in neoplastic transformation.
- Domenick E. Kennedy
- Michael K. Okoreeh
- Marcus R. Clark