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.