DEPENDENCE OF GERMINAL CENTER B-CELLS ON EXPRESSION OF CD21 CD35 FOR SURVIVAL/

Affinity-driven selection of B lymphocytes within germinal centers is critical for the development of high-affinity memory cells and host pr otection. To investigate the role of the CD21/CD35 coreceptor in B cel l competition for follicular retention and survival within the germina l center, either Cr2(+) or Cr2(null) lysozyme-specific transgenic B ce lls were adoptively transferred into normal mice immunized with duck ( DEL) or turkey (TEL) lysozyme, which bind with different affinities. I n mice injected with high-affinity turkey lysozyme, Cr2(null) B cells responded by follicular retention; however, they could not survive wit hin germinal centers. This suggests that CD21 provides a signal indepe ndent of antigen that is required for survival of B cells in the germi nal center.