Localization of 125-I-labelled antigen in germinal centres of mouse spleen: effects of competitive injection of specific or non-cross-reacting antigen.

Studies were performed on localization of I-human γ-globulin in spleen lymphatic tissue germinal centres during the primary and secondary immune response as influenced by competitive injections of specific or non-cross-reacting antigens. Isologous mouse 7S serum protein labelled with I was used as the control. The results of these studies support the following conclusions: (1) Antigen retention in germinal centres during the primary immune reaction is a dynamic process. For some antigens there may be opsonins available at the the time of injection which promote initial localization in germinal centres. However, the continued localization of antigen over weeks and months is a function of specific antibody production. (2) For some period of time, germinal centres are specific to the antigen that stimulated their development, and eventually these centres will respond to a different antigen. (3) Antigen persisting in germinal centres is functional in the development of the secondary immune potential.