ABSTRACT
The biological mechanisms responsible for the long-term maintenance and regulation of immune responses are clearly of major significance. This chapter is concerned with humoral immune responses and the complex biological mechanisms responsible for their maintenance and regulation. Specific antibody is maintained in vivo for months or years and it is catabolized at a reasonably constant rate but it is not produced at a constant rate. The chapter explains the interrelationships between persisting antigen, follicular dendritic cells, and the antibody feedback mechanism in the cyclical production of specific antibody. The evidence that antigen can persist on dendritic cells of the lymph node follicles for months or years is persuasive. One of the most striking characteristics of the antigen retention phenomenon is its strict localization in spleen and lymph node follicles. Electron microscopic studies demonstrated that antigen retained in spleen and popliteal lymph node follicles is localized to the surface of a unique type of cell.
