The generation of memory cells. IV. Immunization with antigen-antibody complexes accelerates the development of B-memory cells, the formation of germinal centres and the maturation of antibody affinity in the secondary response.

Hapten (DNP)-specific B-memory cells were induced by priming mice with soluble or alum precipitated DNP-haemocyanin (KLH) plus Bordetella pertussis or CNP-KLH-anti-DNP antibody complexes at equivalence. Cells from mice given complexes gave a substantial adoptive IgG response five days after priming, whereas those from mice given antigen with conventional adjuvant did not give a comparable response until day 14. Soluble antigen induced poor memory, even 14 days after primary immunization. The emergence of transferable B-memory cells correlated closely with the appearance of germinal centres in lymphoid follicles of the spleen. Furthermore, the relative affinity of the adoptive secondary IgG response induced by priming with complexes was already maximal on day 6. In contrast, the response of memory cells from mice given antigen on alum, increased in affinity between 6 and 23 days after priming. These data support the concept (see Klaus, Humphrey, Kunkl & Dongworth, 1980) that trapping of antigen-antibody complexes in lymphoid follicles induces the formation of germinal centres, which in turn give rise to functional B-memory cells. They further suggest that such retained complexes play a role in selective triggering of high-affinity precursor cells.