Development of CD27+ marginal zone B cells requires GALT

In species other than mouse, little is known about the origin and development of marginal zone (MZ) B cells. Using cross-reactive antibodies, we identified and characterized splenic MZ B cells in rabbits as CD27(+)CD23(-). In rabbits in which organized gut-associated lymphoid tissue (GALT) was surgically removed at birth, we found only CD23(+) follicular (FO) B cells and almost no CD27(+) MZ B cells in the spleen, indicating that GALT is required for the development of splenic MZ B cells. These findings lead us to suggest that commensal microbiota contribute to the development of MZ B cells.