DISRUPTION OF THE BCL6 GENE RESULTS IN AN IMPAIRED GERMINAL CENTER FORMATION

The Bcl6 gene has been identified from the chromosomal translocation b reakpoint in B cell lymphomas, and its products are expressed highly i n germinal center (GC) B cells. To investigate the function of Bcl6 in lymphocytes, we have generated RAG1-deficient mice reconstituted with bone marrow cells from Bcl6-deficient mice (Bcl6(-/-)RM). Lymphogenes is in primary lymphoid tissues of Bcl6(-/-)RM is normal, and Bcl6(-/-) RM produced control levels of primary IgG1 antibodies specific to T ce ll-dependent antigens. However, GCs were not found in these mice. This defect was mainly due to the abnormalities of B cells. Therefore, Bc1 6 is essential for the differentiation of GC B cells.