Hypermutation in Human B Cells in Vivo and in Vitro

Abstract
Abstract: We develop our previous observation that a subpopulation of circulating memory IgM+IgD+CD27+B cells belongs to a separate pathway of differentiation in humans. This subpopulation, which represents 5–25% of peripheral B cells, is also present in spleen in the same proportion and displays a marginal‐zone‐like B cell phenotype. In addition, we describe a short‐time in vitro induction model for somatic hypermutation by using the BL2 Burkitt's lymphoma cell line stimulated by a combination of antibodies directed against different surface receptors. This short‐time assay allows us to show that mutations are stably introduced in one DNA strand of the BL2 VH gene in the G1 phase of the cell cycle.