B Lymphocyte Memory: Role of Stromal Cell Complement and Fc gamma RIIB Receptors

To dissect the influence of CD21/CD35 and Fc gamma RIIB in antigen retention and humoral memory, we used an adoptive transfer model in which antigen-primed B and T lymphocytes were given to sublethally irradiated wild-type mice or mice deficient in CD21/CD35 (Cr2 super(-/-)) or Fc gamma RIIB receptors (Fc gamma RIIB super(-/-)). Cr2 super(-/-) chimeras showed impaired memory as characterized by a decrease in antibody titer, reduced frequency of antibody secreting cells, an absence of affinity maturation, and significantly reduced recall response. The impaired memory in Cr2 super(-/-) chimeras corresponded with the reduced frequency of antigen-specific memory B cells. Interestingly, Fc gamma RIIB super(-/-) chimeras showed a differential phenotype with impaired splenic but normal bone marrow responses. These data suggest that CD21/CD35 on stroma, including follicular dendritic cells, is critical to the maintenance of long-term B lymphocyte memory.